Francesco CANESTRARI

Pubblicazioni

Francesco CANESTRARI

 

158 pubblicazioni classificate nel seguente modo:

Nr. doc. Classificazioni
91 1 Contributo su Rivista
60 4 Contributo in Atti di Convegno (Proceeding)
6 2 Contributo in Volume
1 5 Altro
Anno
Risorse
Interlaboratory Test to Characterize the Cyclic Behavior of Bituminous Interlayers: An Overview of Testing Equipment and Protocols
Proceedings of the RILEM International Symposium on Bituminous Materials. ISBM 2020
Autore/i: Canestrari, F.; Attia, T.; Di Benedetto, H.; Graziani, A.; Jaskula, P.; Kim, Y. R.; Maliszewski, M.; Pais, J. C.; Petit, C.; Raab, C.; Ragni, D.; Rys, D.; Sangiorgi, C.; Sauzeat, C.; Zofka, A.
Editore: Springer Science and Business Media B.V.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The performance assessment of multi-layered pavements strongly depends on the mechanical behavior of the interface between bituminous layers. So far, comprehensive studies have been carried out mainly using quasi-static laboratory tests focusing on the interlayer shear strength at failure. However, it is generally recognized that cyclic shear testing will lead to the determination of parameters which are more closely linked to the performance of pavements under traffic loading than the quasi-static shear tests. This paper outlines the research work that has been carried out within the Task Group 3 “Pavement multilayer system” of the RILEM TC 272-PIM. The activities focused on cyclic shear testing of interfaces in bituminous pavements involve an interlaboratory test with nine participating laboratories. The interface behavior was investigated through both direct shear and torque tests on double-layered specimens extracted from lab compacted slabs prepared by one of the laboratories. The different testing equipment and protocols used by the participating laboratories are presented, highlighting the variety of geometries, loading modes, and testing parameters.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292648 Collegamento a IRIS

2021
Monitoring the evolution of the structural properties of warm recycled pavements with Falling Weight Deflectometer and laboratory tests
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Ingrassia, Lorenzo Paolo; Cardone, Fabrizio; Ferrotti, Gilda; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: In pavement engineering, the use of warm mix asphalt (WMA) technologies can ensure important environmental and technical benefits. However, several uncertainties about WMA still exist, such as long-term field performance and full compatibility with reclaimed asphalt pavement (RAP) or polymer modified bitumen (PMB). In this regard, a full-scale trial section (including three test fields with warm recycled mixtures prepared with different WMA chemical additives and a reference test field with hot recycled mixtures, all containing PMB) was constructed along an Italian motorway and monitored for several years of service life. The evolution of the structural properties was assessed with in-situ Falling Weight Deflectometer (FWD) tests and laboratory tests on extracted cores, both immediately after the construction of the trial section and after more than three years under actual traffic loading. It was found that the reduced working temperatures adopted for theWMAmixes (40°C lower than hot mix asphalt (HMA)) did not penalise the workability and the stiffness immediately after the trial section construction, whereas theHMAmixture experienced higher structural damage (likely due to more severe aging) during the in-service life. The WMA mixes exhibited better stiffness homogeneity and, overall, superior performance and potentially longer service life with respect to the referenceHMA mixture.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/290821 Collegamento a IRIS

2021
Performance Assessment of Asphalt Mixture Produced with a Bio-Based Binder
MATERIALS
Autore/i: Gaudenzi, Elena; Canestrari, Francesco; Lu, Xiaohu; Cardone, Fabrizio
Classificazione: 1 Contributo su Rivista
Abstract: Nowadays, the growing energy costs and pressing worldwide demand for petroleum-based products create a strong need to develop alternative binders deriving from green and renewable sources. Bio-binders (or bitumen added to bio-based materials) can potentially be a viable alternative for the production of bituminous mixture, promoting the circular economy as well as environmental sustainability principles without reducing the overall performance of the mixture. In this context, the current study focuses on evaluation of the effects of a bio-binder on the mechanical response of asphalt concrete (AC) produced with it. In particular, a 10% bio-oil deriving from a by-product of the paper industry has been blended with a conventional 50/70 penetration grade bitumen to obtain the bio-binder. Moreover, plain bitumen having the same consistency was chosen to produce a reference AC. Two dense-graded AC wearing courses were prepared in the laboratory according to Italian technical specifications. A mechanical characterization in terms of indirect tensile strength, indirect tensile stiffness modulus, fatigue response and permanent deformation resistance was performed on gyratory compacted specimens using both conventional and performance tests. In addition, aging and water sensitivity of the AC specimens were evaluated. Overall results highlight that the AC produced with the bio-binder did not show reduced mechanical properties and it was comparable to the reference AC regardless of aging and water conditioning. This highly encourages the use of bio-binder as a viable alternative in asphalt technology.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/290903 Collegamento a IRIS

2020
L’innovativo (e complesso) progetto di ricerca “Extreme Recycling of Asphalt” (ERA): una collaborazione di successo tra mondo imprenditoriale e accademico italiani
RASSEGNA DEL BITUME
Autore/i: Tolentino, F.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277015 Collegamento a IRIS

2020
A review of top-down cracking in asphalt pavements: Causes, models, experimental tools and future challenges
JOURNAL OF TRAFFIC AND TRANSPORTATION ENGINEERING
Autore/i: Canestrari, F.; Ingrassia, L. P.
Classificazione: 1 Contributo su Rivista
Abstract: In the last decades, a new type of distress has been observed more and more frequently on asphalt pavements. This distress, ascribable to fatigue failure, has been named top-down cracking (TDC) because it consists in longitudinal cracks that initiate on the pavement surface and then propagate downwards. A series of surveys recently carried out on Italian motorways highlighted that TDC can affect up to 20%–30% of the slow traffic lane. Therefore, in order to achieve a better understanding of such distress, this paper reviews causes, models and experimental tools and highlights future challenges for TDC. The literature review indicates that TDC can evolve on the pavement surface in three stages (i.e., single crack, sister cracks, alligator cracking) and, below a certain depth, the cracks can form angles of 20°–40° with respect to the vertical plane. Even though multiple factors contribute to TDC development, thick pavements are more likely to fail due to TDC induced by tire-pavement contact stresses, especially in the presence of open-graded friction courses (OGFCs). Moreover, in literature there are several TDC models based on mechanics (e.g., fracture mechanics or continuum damage mechanics) which allow a rigorous study of crack initiation and propagation. Future challenges include the identification of a reliable and feasible test method, among those proposed in literature, to study the TDC performance of asphalt mixtures and the implementation of TDC in pavement management systems (PMSs) through the definition of criteria for TDC recognition in the field as well as for the rehabilitation depth evaluation. Finally, more research is needed for open-graded asphalt mixtures, which present critical drawbacks in terms of TDC.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287661 Collegamento a IRIS

2020
Shear-torque fatigue performance of geogrid-reinforced asphalt interlayers
SUSTAINABILITY
Autore/i: Ragni, D.; Canestrari, F.; Allou, F.; Petit, C.; Millien, A.
Classificazione: 1 Contributo su Rivista
Abstract: Interlayer reinforcement systems represent a valid solution to improve performance and extend the service life of asphalt pavements, reducing maintenance costs. The main issue is that the presence of reinforcement may hinder the full transmission of stresses between asphalt layers, reducing the overall pavement bearing capacity. This study aimed at evaluating the mechanical behavior of geogrid-reinforced asphalt interlayers under cyclic shear loading. To this purpose, a trial section, characterized by three types of interface (reinforced with carbon fiber grid, reinforced with glass fiber grid and unreinforced), was built. Cores were taken from the trial section to carry out shear-torque fatigue tests. Static Leutner shear tests were also performed on cored specimens having the same interface configuration. From data gathered in the present study, shear-torque fatigue tests have proved to be a powerful tool for investigating reinforced specimens. Results clearly ranked the investigated materials, showing that the glass fiber grid has the lowest shear fatigue performance in comparison with the other two interfaces at 20 °C. However, the shear fatigue resistance of glass fiber grid increases significantly at 10 °C. Finally, an interesting correlation was found between cyclic and static shear test results that should be better investigated in future studies.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287660 Collegamento a IRIS

2020
Performance Optimization of Warm Recycled Mixtures
Lecture Notes in Civil Engineering
Autore/i: Cardone, F.; Canestrari, F.; Jiang, X.; Ferrotti, G.
Editore: Springer
Classificazione: 2 Contributo in Volume
Abstract: Warm Mix Asphalt (WMA) technologies are becoming popular due to their ability to reduce mixing and compaction temperatures compared to the conventional hot mix asphalts (HMAs), with remarkable advantages of environment and costs. Moreover, WMA is considered as one of the most promising technology for increasing the re-use of Reclaimed Asphalt (RA) within the mixture although its effectiveness in recycling issues require more dedicated research activities. This paper describes a laboratory investigation aimed at optimizing a dense graded asphalt mixture for wearing course, produced with WMA technology and including up to 30% of RA. WMA mixtures were prepared by using two contents of a plain bitumen, two contents of RA and one chemical additive. A recycled HMA containing lower RA content, according to technical specifications currently applied in Italy, was selected as reference mixture. Strength and stiffness properties, water sensitivity, rutting and cracking resistance were investigated on shear gyratory compacted specimens. The result analysis on stiffness, rutting and fracture properties indicated the possibility to produce suitable WMA mixtures with higher RA contents without penalizing their performance compared to the reference one.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287658 Collegamento a IRIS

2020
Top-down cracking in Italian motorway pavements: A case study
CASE STUDIES IN CONSTRUCTION MATERIALS
Autore/i: Ingrassia, L. P.; Spinelli, P.; Paoloni, G.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Top-down cracking (TDC) is a distress affecting asphalt pavements and consists of longitudinal cracks that initiate on the pavement surface and propagate downwards. In general, TDC is more critical in the case of thick pavements with open-graded friction course (OGFC), which are the typical characteristics of Italian motorway pavements. Recent surveys showed the presence of many longitudinal cracks potentially ascribable to TDC on Italian motorways. Within this context, this study has two main objectives: 1) to define reliable identification criteria allowing to distinguish between TDC and the other types of longitudinal cracks observed and 2) based on the developed criteria, to quantify TDC in Italian motorway pavements. In this regard, a 200 km long trial network (400 km considering both directions) was studied, taking into account the effect of several variables (e.g. geometric characteristics, traffic level, wearing layer type and climate). For this purpose, images of the trial network acquired during pavement monitoring were visually analysed and some control cores were taken. Specific criteria (which can be used in a pavement management system, PMS) were developed to distinguish between the main types of longitudinal cracks observed on the trial network, i.e. TDC, cracks due to heavy vehicles tire blowout and construction joints, based on their geometric features on the pavement surface. It was found that TDC can affect up to 20–30 % of the slow traffic lane. Specifically, the highest TDC concentrations were observed for high traffic levels and OGFC, whereas TDC was absent in the case of a dense-graded wearing layer. Finally, surprisingly the concentration of tire blowout cracks was even higher than TDC. This study provides evidence on the fact that, for thick pavements with OGFC, TDC has to be considered a priority problem to be addressed in both pavement design and maintenance.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287662 Collegamento a IRIS

2020
Evaluation of graphite nanoplatelets influence on the lubrication properties of asphalt binders
MATERIALS
Autore/i: Yan, T.; Ingrassia, L. P.; Kumar, R.; Turos, M.; Canestrari, F.; Lu, X.; Marasteanu, M.
Classificazione: 1 Contributo su Rivista
Abstract: With the major advance in nanotechnology, there has been an emerging interest in applying nanoscale materials to asphalt pavement materials. Among them, considerable interest has been directed to carbon-based nanomaterials, such as carbon nanotubes (CNTs) and graphite nanoplatelets (GNPs). Recent studies have proven that the addition of small percentages of GNPs could significantly reduce the compaction effort required to densify HMA. Viscosity measurements showed, however, that the addition of GNPs increased the viscosity of the binder. This observation pointed towards the presence of a different mechanism responsible for the reduction of compaction effort. A new test method used for lubricants and based on tribology has been recently proposed in order to characterize the lubricating behaviour of asphalt binders. In this study, the tribological characterization of an asphalt binder modified with GNPs was performed. A novel approach in which aggregate surface microtexture was simulated using rough surfaces of the testing fixtures, shows that indeed, the addition of GNPs lowers the friction coefficient and therefore, enhances the lubrication properties of the binder when mixed with mineral aggregates.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276998 Collegamento a IRIS

2020
Chemical, morphological and rheological characterization of bitumen partially replaced with wood bio-oil: Towards more sustainable materials in road pavements
JOURNAL OF TRAFFIC AND TRANSPORTATION ENGINEERING
Autore/i: Ingrassia, L. P.; Lu, X.; Ferrotti, G.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Nowadays, sustainability and circular economy are two principles to be pursued in all fields. In road pavement engineering, they can be put into practice through the partial substitution of bitumen with industrial residues and by-products deriving from renewable materials. Within this framework, this paper presents an extensive investigation of the chemical, morphological and rheological properties of bio-binders obtained by mixing a conventional 50/70 bitumen with different percentages by weight (0, 5%, 10% and 15%) of a renewable bio-oil, generated as a residue in the processing of wood into pulp and paper. Results show that overall the bio-oil provides a softening effect, which, in terms of performance, leads to an improvement of the low-temperature behaviour and fatigue resistance with respect to the control bitumen, in spite of an increased tendency to permanent deformation. Although no chemical reaction appears to occur after blending, the peculiarities of the bio-oil affect the chemistry of the resulting bio-binders, whereas no phase separation is observed from the microscopic analysis. In addition, a Newtonian behaviour, an unchanged temperature susceptibility and a good fitting of 1S2P1D model to the rheological data are found, regardless of the bio-oil percentage considered. These promising outcomes suggest that such bio-binders can be favourably employed for several applications in road pavements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276995 Collegamento a IRIS

2020
Analysis of shear-torque fatigue test for bituminous pavement interlayers
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Ragni, D.; Ferrotti, G.; Petit, C.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The laboratory characterisation of bituminous interlayers is a challenging issue because of the difficulty of establishing loading conditions that can simulate field behaviour. This paper describes a shear-torque fatigue test procedure aimed at investigating the fatigue behaviour of bituminous pavement interlayers. A preliminary experimental investigation, able to evaluate the damage process occurring in both single- and double-layered specimens, showed that the presence of the interface constitutes a weakness zone, noticeably influencing the shear fatigue performance of the pavement structure. Thus, a model for the description of the evolution of the interlayer damage by using the variation of the interlayer complex shear modulus was proposed and preliminarily validated. Moreover, a new fatigue failure criterion has been proposed to be used in the result analysis of the shear-torque fatigue tests.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/280048 Collegamento a IRIS

2020
Use of acoustic techniques to analyse interlayer shear-torque fatigue test in asphalt mixtures
INTERNATIONAL JOURNAL OF FATIGUE
Autore/i: Ragni, D.; Takarli, M.; Petit, C.; Graziani, A.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Shear-torque tests were used for the first time to assess the fatigue behaviour of double-layered asphalt specimens. During the test, an acoustic emission (AE) technique was used to evaluate the damage process leading to failure. Results showed that the application of cyclic loading led to the decrease of the complex shear modulus, until the physical separation of the two layers. AE analysis showed that damage mostly occurred in the interlayer zone. The comparison between mechanical and AE results suggested that the damage evolution phase occurred when approaching the end of the test when the stiffness decrease was about 70%.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276102 Collegamento a IRIS

2020
Analysis of Fatigue and Healing Properties of Conventional Bitumen and Bio-Binder for Road Pavements
MATERIALS
Autore/i: GAUDENZI, ELENA; CARDONE, Fabrizio; Lu, Xiaohu; CANESTRARI, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: The analysis of fatigue behavior of bituminous binders is a complex issue due to several time-temperature dependent phenomena which interact simultaneously, such as damage accumulation, viscoelasticity, thixotropy, and healing. The present research involves rheological measurements aimed at evaluating the fatigue behavior and compares the self-healing capability of two plain bitumen and a bio-binder obtained by partially replacing one of the plain bitumen with a renewable bio-oil. Healing potential was assessed by means of an experimental approach previously implemented for modified bitumen and bituminous mastic and based on the use of a dynamic shear rheometer (DSR). The effects of some variables such as bitumen type, bio-oil addition, and aging on the healing potential of binders were taken into account. Results showed that the above-mentioned method for healing analysis is also suitable for conventional and bio-add binders. Outcomes of the experimental investigation highlight that fatigue and self-healing are mainly dependent on binder consistency and also affected by aging. Finally, the addition of bio-oil may induce even better performances in terms of healing potential compared to conventional bitumen, especially in aged condition.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273157 Collegamento a IRIS

2020
Effect of geocomposite reinforcement on the performance of thin asphalt pavements: Accelerated pavement testing and laboratory analysis
CASE STUDIES IN CONSTRUCTION MATERIALS
Autore/i: Ingrassia, L. P.; Virgili, A.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The objective of this study is to assess the effect of geocomposite reinforcement on fatigue cracking, reflective cracking and permanent deformation accumulation of thin asphalt pavements. For this purpose, a full-scale trial section was constructed with different interfaces: unreinforced (reference) and reinforced with three types of geocomposites, formed by the combination of a bituminous membrane with a fabric or grid. The experimental program included accelerated pavement testing (APT) carried out by means of Fast Falling Weight Deflectometer (FastFWD) and laboratory tests (three point bending tests) on samples taken from the trial section. After APT, significant permanent deflections were observed, likely due to the plastic yielding of the unbound layers. Nevertheless, all the geocomposites improved the permanent deformation resistance as compared to the unreinforced pavement by reducing the vertical strain at the top of the subgrade. Moreover, the geocomposites increased the energy necessary for the crack propagation by three to eight times with respect to the unreinforced pavement. Overall, these findings indicate that the use of geocomposites can extend the service life of thin asphalt pavements in terms of both cracking and permanent deformation accumulation.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276997 Collegamento a IRIS

2020
Fast falling weight accelerated pavement testing and laboratory analysis of asphalt pavements reinforced with geocomposites
Proceedings of the 5th International Symposium on Asphalt Pavements & Environment (APE)
Autore/i: Ragni, D.; Montillo, T.; Marradi, A.; Canestrari, F.
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Many reinforcement systems have been designed to improve fatigue life and to prevent or mitigate reflective cracking and rutting in asphalt pavements. The goal of this research was to assess the effectiveness of asphalt pavement rehabilitation with geocomposites to limit fatigue cracking, reflective cracking and rutting by using Accelerated Pavement Testing (APT) and laboratory testing. APT was used to evaluate the pavement performance, simulating the effects of long-term vehicular traffic on the pavement structure in a relatively short period of time. Accelerated pavement tests were performed using the Fast Falling Weight Deflectometer (FastFWD) equipment in a trial section characterized by different types of interfaces (reinforced with geocomposites and unreinforced). In addition, two types of specimen were taken from the trial section to carry out laboratory testing: cores for Ancona Shear Test Research and Analysis (ASTRA) tests and beams for three point bending (3PB) tests. The APT and 3PB tests results demonstrated that the geocomposites investigated are an effective method to enhance asphalt pavement performance. Moreover, ASTRA tests showed that the application of geocomposite at the interface causes a de-bonding effect between asphalt layers that could be beneficial to promote stress-relieving in case of reflective cracking and thermal cracking.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277012 Collegamento a IRIS

2020
Investigating the “circular propensity” of road bio-binders: Effectiveness in hot recycling of reclaimed asphalt and recyclability potential
JOURNAL OF CLEANER PRODUCTION
Autore/i: Ingrassia, L. P.; Lu, X.; Ferrotti, G.; Conti, C.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: In pavement engineering, the use of bio-binders and reclaimed asphalt (RA) promotes the principles of sustainability and circular economy, without penalizing or even improving the performance. In this regard, this study focuses on the “circular propensity” of bio-binders obtained by partially replacing a conventional bitumen with a bio-oil generated as a residue by the wood and paper industries. Specifically, the objectives are: 1) to assess the effectiveness of bio-binders in the hot recycling of traditional RA and 2) to evaluate, in a long-term perspective, their recyclability potential. For this purpose, two severely aged binders (one “RAP” binder recovered from reclaimed asphalt and one laboratory-produced “Bio-RAP” binder) and two fresh binders (one bio-binder and one bitumen) are blended to reproduce four hot recycled binders. The mechanical behaviour and the aging susceptibility of these blends are compared to those of a control virgin bitumen. The experimental investigation includes conventional tests, rheological testing and modelling (modified CAM model) as well as chemical analysis (Fourier transform infrared spectroscopy). The main results indicate that the hot recycling of reclaimed bio-asphalt (bio-RA) may lead to mixtures less susceptible to cracking as compared to the recycling of conventional RA, as well as the use of bio-binders in the hot recycling of conventional RA may be beneficial in terms of cracking. Even though the blends with the bio-binder are characterized by a lower aging rate, the permanent deformation behaviour of all the recycled blends studied is comparable in unaged and short-term aged conditions, i.e. the circumstances under which rutting is usually a concern. Finally, the recycled blends show significantly lower aging susceptibility than the control bitumen. Overall, these results suggest that the bio-binders studied are effective in the hot recycling of RA and 100% recyclable, and their use in asphalt pavements can lead to significant technical and environmental benefits.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276996 Collegamento a IRIS

2019
Research and Engineering for Resilient Infrastructures and Environment Protection
The First Outstanding 50 Years of “Università Politecnica delle Marche”
Autore/i: Bocci, Maurizio; Brocchini, Maurizio; Canestrari, Francesco; Cardone, Fabrizio; Corvaro, Sara; Darvini, Giovanna; Ferrotti, Gilda; Graziani, Andrea; Lorenzoni, Carlo; Mancinelli, Alessandro; Postacchini, Matteo; Soldini, Luciano; Virgili, Amedeo
Classificazione: 2 Contributo in Volume
Abstract: We discuss the contribution of the research groups that work at UNIVPM in the field of infrastructure engineering to the design of resilient hydraulic and transportation infrastructures and related solutions for the protection of the environment. After recalling the long history of research and engineering intervention of the groups of Hydraulics and Transportation Infrastructures of UNIVPM, we show how the activities of such groups are becoming of increasing importance in response to the growing request of innovative solutions for resilient infrastructures (e.g. coastal protection and maritime structures, road and airport pavements) and environment protection (e.g. coastal and river flood, air pollution, waste recycling and materials reuse). Such activities have been recently boosted by the resources made available to the two groups through the “Dipartimenti di Eccellenza” award, which largely focuses on the issue of engineering for resilient built and natural environments. A projection in the future of the activities of above is also proposed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/273420 Collegamento a IRIS

2019
Sustainable Engineering for Resilient Built and Natural Environments
The First Outstanding 50 Years of “Università Politecnica delle Marche”
Autore/i: Alici, Antonello; Bocci, Maurizio; Bonvini, Paolo; Brocchini, Maurizio; Calamai, Alessandro; Canestrari, Francesco; Capozucca, Roberto; Carbonari, Alessandro; Carbonari, Sandro; Cardone, Fabrizio; Clementi, Francesco; Clini, Paolo; Cocchi, Giammichele; Corvaro, Sara; Darvini, Giovanna; Davì, Fabrizio; Dezi, Luigino; Di Giuseppe, Elisa; D’Orazio, Marco; Ferretti, Maddalena; Ferrotti, Gilda; Gara, Fabrizio; Giretti, Alberto; Graziani, Andrea; Lancioni, Giovanni; Lemma, Massimo; Lenci, Stefano; Lorenzoni, Carlo; Malinverni, Eva Savina; Mancinelli, Alessandro; Mariano, Fabio; Mentrasti, Lando; Mondaini, Gianluigi; Montecchiari, Piero; Munafò, Placido; Naticchia, Berardo; Postacchini, Matteo; Quagliarini, Enrico; Quattrini, Ramona; Ragni, Laura; Serpilli, Michele; Soldini, Luciano; Virgili, Amedeo; Zampini, Giovanni
Editore: Springer
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/272866 Collegamento a IRIS

2019
Influence of different fillers and SBS modified bituminous blends on fatigue, self-healing and thixotropic performance of mastics
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Mazzoni, G.; Virgili, A.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The prediction of asphalt pavement performance is closely linked to the behaviour of mastic, consisting of filler and bitumen, which can be modelled as viscoelastic material. The purpose of this study is to investigate the effect of different fillers and bituminous blends on mastic fatigue response, considering recoverable phenomena in viscoelastic materials (thixotropy and self-healing) that concurrently occur. Three fillers (limestone, basalt and Portland cement) and three aged polymer modified bitumen contents (0%, 45% and 100%) were blended with a virgin polymer modified bitumen obtaining nine mastics characterised in terms of fatigue, self-healing and thixotropy using a Dynamic Shear Rheometer. Data obtained are analysed through a model previously adopted for polymer modified bitumens and mastics, allowing the determination of the fatigue endurance limit. Results show that the presence of filler with increasing particle density and/or Rigden voids causes a higher mastic stiffness without a clear trend on fatigue performance. In fact, great attention should be put on filler-bitumen interactions based on the physicochemical nature of filler. Moreover, whatever the filler considered, an enhancement in the fatigue endurance limit is detected in the mastics blended with a percentage of aged polymer modified bitumen (up to 45%), promoting the addition of Reclaimed Asphalt to obtain more performing and sustainable recycled mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/258328 Collegamento a IRIS

2019
Renewable materials in bituminous binders and mixtures: speculative pretext or reliable opportunity?
RESOURCES CONSERVATION AND RECYCLING
Autore/i: Ingrassia, L. P.; Lu, X.; Ferrotti, G.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Bitumen is the most employed binder in road pavements and derives from petroleum, which is a non-renewable resource that is progressively depleting. Therefore, the current challenge for road industry is to use renewable materials (i.e. bio-materials not subjected to depletion) in partial replacement of bitumen, thus reducing carbon footprint and making the sector less dependent on petroleum-based products. Specifically, the trend is to utilize bio-materials that are obtained as by-products from industrial processes or as wastes from the everyday life, avoiding their disposal in landfills, in accordance with the principles of sustainability and circular economy. Thus, research in this field is very promising and attractive nowadays. However, in order to understand whether the application of renewable materials represents a reliable and viable solution or just a speculative pretext for research, a rigorous scientific approach must be adopted. For this purpose, the paper provides an overview of the use of renewable materials in bituminous binders and mixtures, focusing on the necessary requirements that they should meet, their effects on performance, and health, safety and environment aspects. Based on the analysis of available literature, a comprehensive experimental approach for evaluating bio-materials in bituminous applications is also proposed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263622 Collegamento a IRIS

2019
Tribological characterization of graphene nano-platelet (GNP) bituminous binders
Airfield and Highway Pavements 2019: Innovation and Sustainability in Highway and Airfield Pavement Technology - Selected Papers from the International Airfield and Highway Pavements Conference 2019
Autore/i: Ingrassia, L. P.; Lu, X.; Marasteanu, M.; Canestrari, F.
Editore: American Society of Civil Engineers (ASCE)
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: According to recent research, the addition of graphene nano-platelets (GNPs) to bitumen can lead to a considerable improvement of the compactability of bituminous mixtures, without reducing the viscosity of the binder, meaning that other mechanisms are responsible for this phenomenon. In this regard, the present study focuses on the characterization of the lubricating behaviour of GNP binders obtained by adding 3% and 6% GNPs to a plain PG 58-28 bitumen, through a novel tribological approach recently proposed in literature. In addition, the experimental program is completed by viscosity tests. Results show that GNP addition leads to an increase in both viscosity and friction, which in general is greater for higher GNP contents, for all testing temperatures. A good correlation between viscosity and minimum friction exists in the elasto-hydrodynamic regime of lubrication, whereas the results obtained in the boundary and mixed regimes may be significantly affected by the testing conditions considered. Specifically, the use of different substrates is suggested for future work, in order to achieve a better understanding of the mechanisms that govern the compaction behaviour of bituminous mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/277007 Collegamento a IRIS

2019
Linear viscoelastic characterisation of bituminous mixtures using random stress excitations
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Graziani, A.; Cardone, F.; Virgili, A.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The three-dimensional linear viscoelastic characterisation of bituminous mixtures can be performed with the concurrent measurement of the complex Young’s modulus and the complex Poisson’s ratio. This normally requires the application of sinusoidal excitations leading to small strain amplitudes. Since in the linear domain the effects of sinusoidal excitations are independent of each other, the material behaviour can also be obtained using a broad-band multi-frequency excitation. In this study, the complex Young’s modulus and Poisson’s ratio of a bituminous mixture was obtained by applying a random wave axial stress to cylindrical specimens and measuring their strain response in the axial and transverse direction. The frequency response functions representing the Young’s modulus and Poisson’s ratio were calculated using a conventional spectral analysis approach. Sinusoidal tests at different strain levels were also carried out as a reference. Applying random waves at 10, 20 and 30°C provided results with a high signal-to-noise ratio at frequencies between 0.1 Hz and 40 Hz for the Young’s modulus and between 1 and 90 Hz for Poisson’s ratio. For both functions the results validate the time-temperature superposition principle. The direct comparison with the results of sinusoidal testing confirms the accuracy of the frequency response functions measured with the random wave approach and shows their potential
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267167 Collegamento a IRIS

2019
Ageing of rejuvenated bitumen in hot recycled bituminous mixtures: influence of bitumen origin and additive type
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Bocci, E.; Mazzoni, G.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The present study aims at investigating the evolution of the rheological properties of a primary bitumen with ageing (first service life), hot recycling (50/50 blending of virgin and aged bitumen, without adding additives or adding with three different rejuvenators) and re-ageing (service life after RAP hot recycling). RTFOT and PAV equipment were used to simulate bitumen ageing in laboratory and DSR allowed analysing the rheological behaviour. Results show that the hot recycled bituminous blends including a properly selected and dosed rejuvenator can undergo a less severe oxidation than virgin bitumen and can be less stiff at the end of the service life. The comparison with the results obtained in a parallel research, using a bitumen produced through a visbreaking process, proved that the latter is more unstable and exhibits a more detrimental ageing.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276991 Collegamento a IRIS

2019
Chemical and rheological investigation on the short- and long-term aging properties of bio-binders for road pavements
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Ingrassia, L. P.; Lu, X.; Ferrotti, G.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: In recent years, due to growing environmental concerns, sustainability and circular economy have become two issues of crucial importance. In road engineering, in order to pursue such principles, one of the main current trends is to employ industrial residues and by-products deriving from renewable materials in partial substitution of petroleum-based bitumen. However, uncertainty on the durability and long-term performance of such materials still exists. In this regard, this paper focuses on the short- and long-term aging properties of bio-binders obtained by partially replacing a 50/70 bitumen with different percentages of a renewable bio-oil generated as a by-product by the wood and paper industries. The experimental investigation carried out includes conventional tests, chemical analyses as well as rheological testing and modelling with 2S2P1D model. Conventional bitumens were also tested for comparison purposes. The main chemical results indicate that, despite a small amount of additional oxidized compounds related to esters, the bio-oil addition significantly inhibits the formation of carbonyl compounds and reduces the aromaticity of the binders. In terms of performance-related properties, the permanent deformation resistance and the fatigue resistance of these bio-binders are generally comparable to those of traditional bitumens having similar penetration grade, without any specific drawback. Moreover, a linear material-dependent relationship was found between chemical and rheological changes induced by aging as well as the chemical and rheological parameters most strictly related to the binders’ oxidation were identified and considered as aging indicators. Based on the evolution of these parameters, the bio-binders investigated in this study may have comparable or even better aging resistance with respect to conventional bitumens with similar penetration grade. Therefore, such bio-binders can be considered an effective sustainable alternative to traditional bituminous binders.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276994 Collegamento a IRIS

2019
Experimental characterization of the 3D linear viscoelastic behavior of cold recycled bitumen emulsion mixtures
JOURNAL OF TRAFFIC AND TRANSPORTATION ENGINEERING
Autore/i: Graziani, A.; Godenzoni, C.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Cold mixtures with bitumen emulsion are produced at ambient temperature, leading to substantial reductions of energy consumption and atmospheric emissions. In cold recycling applications, cement is normally used to improve the mixture performance. Thus, the rheological behavior of cold recycled mixtures is different from that of conventional hot mixtures because it is due to the interaction of fresh bitumen, aged bitumen and cementitious bonds. In this study, we investigated the three-dimensional (3D) linear viscoelastic (LVE) behavior of a cement-bitumen treated material (CBTM) mixture fabricated using bitumen emulsion and cement. For comparison, we also investigated the 3D LVE behavior of hot-mix asphalt containing 25% of reclaimed asphalt and fabricated using polymer-modified binder. Sinusoidal axial tests on cylindrical specimens, were carried out at various temperatures (from 0 °C to 50 °C) and frequencies (from 0.1 to 12 Hz). The complex Young's modulus E∗ and the complex Poisson's ratio v∗ were determined through the measurement of axial and transverse strain. We show that when considering E∗, CBTM mixtures may be considered thermo-rheologically simple and the Huet-Sayegh model can be used to simulate the frequency–temperature dependence. On the other hand, when considering v∗ the behavior of CBTM mixtures is very different from that of hot mix asphalt. In particular, its absolute value is almost constant and very close to 0.15.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/271212 Collegamento a IRIS

2019
Experimental investigation on the bond strength between sustainable road bio-binders and aggregate substrates
MATERIALS AND STRUCTURES
Autore/i: INGRASSIA, LORENZO PAOLO; CARDONE, Fabrizio; CANESTRARI, Francesco; Lu, Xiaohu
Classificazione: 1 Contributo su Rivista
Abstract: Interest is growing on the application of bio-binders in road pavements. However, currently there is a lack of data concerning the adhesion between bio-binders and aggregates, which is a crucial aspect to ensure adequate performance and durability of bituminous mixtures, especially in the presence of water. In this regard, the present investigation focuses on the evaluation of the binder bond strength (BBS) between bio-binders, characterized by different percentages of a renewable wood bio-oil and different aging levels, and aggregate substrates (limestone and porphyry), in dry and wet conditions. Preliminarily, the binders were subjected to viscosity tests to determine BBS application temperatures. The main results show that the bio-binders studied exhibit a good adhesion with limestone both in dry and wet conditions as well as with porphyry in dry conditions, resulting in cohesive failures. For porphyry substrate, after wet conditioning, a progressive transition from adhesive to cohesive failures is observed as the bio-oil content increases, indicating that the bio-oil might improve the adhesion between bitumen and siliceous aggregates. Based on previous findings on the chemical characteristics of the bio-binders, the contribution of the bio-oil to the adhesion may be attributed to its high content of esters. Overall, the results suggest that the use of bio-binders in road pavements could lead to significant benefits in terms of performance and resistance to moisture damage.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267828 Collegamento a IRIS

2019
Influence of chemical additives for warm mix asphalts on the short-term ageing of a plain bitumen
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Ragni, D.; Ferrotti, G.; Lu, X.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Over the last years, the use of warm mix asphalt (WMA) in asphalt industry allows important reductions in production and compaction temperatures guarantying relevant environmental benefits. However, the most proper laboratory procedure for short-term ageing of WMAs must still be defined. This study aims at evaluating the effect of temperature and chemical additives on bitumen short-term ageing. For this purpose, a 70/100 pen-grade bitumen and two chemical additives were investigated in terms of conventional (penetration, softening point), viscosity and rheological tests, as well as FTIR-ATR analysis. As expected, binders aged at lower temperatures show reduced oxidation as compared to those aged at higher temperatures, implying a lower oxidative hardening. In general, aged binders containing the chemical additives show a reduction of the effect of ageing, or anti-ageing effect. Moreover, the rheological model parameters of the binders present good correlations with penetration values and softening point temperatures, as well as with the chemical parameters determined by FTIR-ATR.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276992 Collegamento a IRIS

2019
Cyclic interlayer testing in bituminous pavements
7th International Conference "Bituminous Mixtures and Pavements"
Autore/i: Ragni, Davide; Graziani, Andrea; Canestrari, Francesco
Editore: CRC Press
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Interlayer bonding in bituminous pavements is assessed by measuring the interface shear strength (ISS) of double-layered specimen, using monotonic tests. However, dynamic shear testing better simulates the actual traffic loads. The RILEM Technical Committee “Phase and Interphase behavior of bituminous Materials” (PIM) organized an interlaboratory test aimed at comparing different equipments employed to obtain the dynamic shear characterization of multilayer bituminous systems. This paper describes the experimental activities carried out at Università Politecnica delle Marche, specifically organization of the interlaboratory test, preparation of the double-layered samples to be tested by the participating laboratories and development of a new device for performing cyclic interface testing. The results include the ISS of the double-layered samples measured with the ASTRA and Leutner devices. Moreover, the results of the cyclic Leutner device are presented along with the preliminary outcomes obtained with the new cyclic ASTRA device, both in terms of stiffness and cumulative damage.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263583 Collegamento a IRIS

2018
Effect of temperature and chemical additives on the short-term ageing of polymer modified bitumen for WMA
MATERIALS & DESIGN
Autore/i: Ragni, D.; Ferrotti, G.; Lu, X.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Nowadays warm mix asphalt (WMA) is recognized as a very competitive alternative to hot mix asphalt (HMA). This technology allows to obtain an excellent and environmentally-friendly material for road construction. This paper focuses on the effect of a reduced short-term ageing temperature on the binder behaviour and on the effect of WMA chemical additives on the performance of short-term aged binders. Three asphalt binders (one polymer modified bitumen combined with two WMA chemical additives) were aged through the rolling thin film oven test (RTFOT) at different temperatures (120, 130 and 163 degrees C). Conventional, rheological and chemical tests were used for characterising the binders. Lower ageing temperatures provided reduced oxidation, implying lower oxidative hardening but also reduced permanent deformation resistance. A general reduction of ageing effects is observed in the WMA binders, with both positive (moderate deceleration of the ageing process) and negative (more noticeable reductions in the permanent deformation resistance) outcomes. The microscopic analysis showed that the chemical additive likely alters the structural interactions of bitumen and polymer. A comparison between WMA binders short-term aged in laboratory and in field, indicates that the RTFOT performed at reduced temperature could properly simulate the field ageing when WMA production temperatures are considered.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263651 Collegamento a IRIS

2018
Bituminous binder
Testing and characterization of sustainable innovative bituminous materials and systems. State-of-the-art report of the RILEM technical committee 237-SIB
Autore/i: Porot, Laurent; Soenen, Hilde; Besamusca, Jeroen; Apeagyei, Alex; Grenfell, James; Vansteenkiste, Stefan; Chailleux, Emmanuel; Gaudefroy, Chaturabong; Preeda, Vincent; Tozzo, Cristina; Artamendi, Ignacio; Sybilski, Darius; Martinez, Francisco Barcelo; Said, Safwat F.; Partl, Manfred N.; Canestrari, Francesco; Hauser, Elisabeth; Wistuba, Michael
Editore: Springer Nature
Luogo di pubblicazione: Cham
Classificazione: 2 Contributo in Volume
Abstract: One of the most important aspects of asphalt pavement deterioration is the ingress of water in pavement which leads to loss of the material characteristics, even material integrity with loss of aggregates. Thus the behaviour of asphalt mixture under moisture conditions is one of the key parameter for specifications. It’s a complex phenomenon which is influenced amongst other things by materials properties with wetting, cohesion and adhesion of bituminous binder and by environmental conditions with temperature, moisture, loading and layer type. It has been a research subject for a very long time and still not precisely described. A large number of test methods is available to estimate the affinity between aggregates and bituminous binders. These test methods can be subdivided in different ways; a first distinction can be based on the presence or absence of water during the test procedure. If water is present, the evaluation is in fact referred to as water sensitivity or moisture damage testing. Another distinction can be based on the type of sample that is evaluated. The test sample can be loose aggregates coated with a bituminous binder or a compacted asphalt mix sample. Lastly the individual components, bitumen and aggregate, can be tested separately through intrinsic properties. Furthermore, test results can also be based on the quantification of the test results, whether this is based on a qualitative or a quantitative evaluation. In RILEM TC 237 SIB, TG1 the main purpose was to evaluate common test methods, used to assess the affinity of bitumen to aggregate surfaces, to determine, if possible, the repeatability and reproducibility and to give recommendations for improvement. In this study both binders and aggregates have been considered. Three bituminous binders, two unmodified from different sources, one polymer modified binder, and four aggregate types, with different mineralogy, have been selected. The test methods considered in the study include the rolling bottle test, the boiling water stripping test and the bitumen bond strength test; also surface energy was investigated. This chapter presents the results of these tests and their accuracy.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263666 Collegamento a IRIS

2018
Characterisation of warm recycled porous asphalt mixtures prepared with different WMA additives
EUROPEAN JOURNAL OF ENVIRONMENTAL AND CIVIL ENGINEERING
Autore/i: FRIGIO, FRANCESCA; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: The use of Reclaimed Asphalt Pavement (RAP) into new asphalt mixtures and the reduction in the production temperatures by means of Warm Mix Asphalt (WMA) additives are two recognised solutions for sustainable pavements. Despite their environmental advantages, the reduced production temperatures of WMA mixtures may lead to rutting and moisture susceptibility issues. Such concerns need to be properly investigated, particularly in case of porous asphalt mixtures (PA) due to their low durability and high water sensitivity. The objective of this study is to evaluate the feasibility to reduce the production temperature of recycled PA including 15% of coarse RAP aggregates; three different WMA additives were selected (organic, chemical additive and zeolite) to produce PA mixtures at 130 °C. One HMA mixture was also prepared at 170 °C and an additional WMA mixture was prepared at reduced temperature without any WMA additive for comparison purposes. The experimental programme focused on compactability and durability properties of the PA mixtures. Results highlight the issues related to the reduced production temperatures of PA mixtures, particularly in terms of moisture susceptibility. Only the presence of the chemical additive in the mixture ensures adequate water resistance, although it does not guarantee short-term performance comparable to the HMA mixture.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/245774 Collegamento a IRIS

2018
Advanced interface testing of grids in asphalt pavements
RILEM State-of-the-Art Reports
Autore/i: Canestrari, Francesco; D’Andrea, Antonio; Ferrotti, Gilda; Graziani, Andrea; Partl, Manfred N.; Petit, Christophe; Raab, Christiane; Sangiorgi, Cesare
Editore: Springer Netherlands
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/254084 Collegamento a IRIS

2018
Influence of rejuvenators on the aging of bitumen in hot recycled asphalt mixtures
JOURNAL OF TRAFFIC AND TRANSPORTATION ENGINEERING
Autore/i: Mazzoni, Giorgia; Bocci, Edoardo; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: The use of reclaimed asphalt pavement (RAP) in new hot mix asphalt (HMA) by means of hot recycling techniques generates the advantage linked to the exploitation of both lytic and bituminous component, consequently leading to the decrease of both virgin aggregates and bitumen supplying. However, many agencies and public administration authorise RAP percentages ranges from 10% to 30% in hot recycling. The main reason for such a low amount of allowable RAP content is related to the aged bitumen contained in the RAP materials, which is more brittle than a virgin bitumen leading to a final mixture more susceptible to fatigue, thermal and reflection cracking. The use of rejuvenators has the potential to restore rheology and chemical components of aged RAP bitumen, thus allowing a significant increase in the amount of RAP to be properly implemented in HMA. The experimental investigation is described in this paper and carried out through a dynamic shear rheometer (DSR) which provides the rheological characterisation of a paving grade bitumen during its overall service life including its reuse in hot recycling by adopting different rejuvenators. Results show that rejuvenators modify bitumen chemistry and consequently rheology by enhancing the viscous response. Moreover, it was observed that oxidation is less harmful, in terms of stiffness increase, on the 50/50 aged bitumen - virgin bitumen blends (rejuvenated or not) than on the virgin bitumen. Moreover, the addition of a rejuvenator in a bituminous blend containing 50% of bitumen reactivated from RAP could lead to a corresponding composite bituminous phase less subjected to ageing phenomena and even less stiff at the end of service life than the associated virgin bitumen alone.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263667 Collegamento a IRIS

2018
Tribological characterization of bituminous binders with Warm Mix Asphalt additives
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Ingrassia, L. P.; Lu, X.; Canestrari, F.; Ferrotti, G.
Classificazione: 1 Contributo su Rivista
Abstract: Warm Mix Asphalt (WMA) technologies allow reducing production, laying and compaction temperatures of bituminous mixtures, leading to relevant environmental and technical benefits. According to recent studies, some WMA additives lead to this temperature reduction by potentially improving the lubricating properties (i.e. the tribological behaviour) of the bituminous binder. In this study, the effect of a chemical and a wax additive on the tribological behaviour of two base bituminous binders was investigated, by considering different percentages of additive. All the binders were preliminarily characterized with Fourier Transform Infrared Spectroscopy (FTIR) and viscosity analysis. After optimizing the test procedure, tribological tests were carried out with a ball-on-three-plates fixture at 85 °C and 120 °C. A statistical analysis was also performed on the tribological results to evaluate the statistical significance of the differences between the binders. Results showed that the additives might alter the oxidative state of the binder, the chemical additive is able to modify the tribological behaviour of the binder, the wax additive acts solely on the viscosity and the effect of the additive depends on the chemical composition of the base binder. Moreover, a correlation between the minimum friction and the viscosity was found.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263628 Collegamento a IRIS

2017
Warm recycling of flexible pavements: Effectiveness of Warm Mix Asphalt additives on modified bitumen and mixture performance
JOURNAL OF CLEANER PRODUCTION
Autore/i: STIMILLI, ARIANNA; VIRGILI, AMEDEO; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: In pavement industry, environmental and economical sustainability stimulates technical solutions able to drastically decrease pollutants and energy costs caused by high production temperatures. In this sense, recent research efforts focused on innovative technologies able to significantly reduce mixing and compaction temperature. The so called Warm Mix Asphalts (WMA) are bituminous mixtures produced at reduced temperatures through specific additives based on different mechanisms. The novelty of WMA technologies determines a lack of experience about their effectiveness, which requires dedicated research activities, especially when polymer modified bitumens and Reclaimed Asphalt Pavement (RAP) are used. Given this context, the present study proposes a comprehensive laboratory investigation on dense-graded mixtures produced through different WMA additives representative of the main categories currently available on the market (i.e. chemical, organic and water-based). Mixtures were prepared including Styrene-Butadiene-Styrene polymer modified bitumen and 25% of RAP to evaluate potential benefits deriving from the combination of warm and recycling techniques. For a complete understanding of WMA additive effects, mechanical tests (i.e. compactability, stiffness, fatigue) carried out on mixtures in a broad range of loading configurations were integrated by rheological analyses on bitumens. Results indicate that lower production temperatures allowed a significant decrease in stiffness, effectively balancing the inclusion of RAP material without penalizing mixture performance. Compactability, volumetric and fracture properties indicate the possibility to produce suitable recycled warm mixtures when the appropriate WMA additive is selected. The chemical additive appeared able to provide overall improved performance, whereas the organic additive made the mixture brittle and susceptible to permanent cracking.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/250298 Collegamento a IRIS

2017
Estimation of low-temperature performance of recycled asphalt mixtures through relaxation modulus analysis
COLD REGIONS SCIENCE AND TECHNOLOGY
Autore/i: STIMILLI, ARIANNA; VIRGILI, AMEDEO; CANESTRARI, FRANCESCO; Bahia, Hussain U.
Classificazione: 1 Contributo su Rivista
Abstract: In cold climates, pavements undergo extreme thermal conditions which cause premature cracking and failure. The inclusion of Reclaimed Asphalt Pavement (RAP) could worsen this tendency due to the reclaimed bitumen stiffening effects. However, nowadays strict economic and environmental sustainability requirements strongly encourage the use of high RAP content in asphalt mixes. In this context, this paper discusses the low temperature performance of mixtures designed with 40% RAP according to the Bailey method. Different bitumen contents and polymer modification levels were employed. A mixture with 25% of unfractioned RAP was employed as the reference mixture. Laboratory tests were performed through Asphalt Thermal Cracking Analyzer (ATCA) by applying thermal loadings on restrained and unrestrained asphalt beams. Based on experimental data the relaxation modulus was evaluated to rank the materials. Its accurate determination is fundamental for designing long lasting pavements with proper performance at low temperature. The analysis was performed through a new analytical methodology for obtaining the relaxation modulus master curve by measuring thermally induced stress and strain. The solution, based on Boltzmann's equation and pseudo-variables concepts, accounts for time and temperature dependency of bituminous materials, avoiding complex integral transformations. The proposed solution successfully integrates the current ATCA analysis providing reliable estimations of relaxation properties fundamental in modelling of pavement behavior. Mixtures containing 40% RAP demonstrated enhanced relaxation capabilities at low temperature showing significant improved behaviours than the reference mixture. Although high amount of reclaimed material, proper selection of RAP and type and quantity of virgin bitumen can improve low temperature performance.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/245769 Collegamento a IRIS

2017
Fatigue, self-healing and thixotropy of bituminous mastics including aged modified bitumens and different filler contents
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: MAZZONI, GIORGIA; STIMILLI, ARIANNA; CARDONE, Fabrizio; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Bituminous mastic is a self-healing viscoelastic material. Recoverable phenomena, such as thixotropy and self-healing capability, are recognised as an important resource for the development of sound road pavements. The experimental investigation described in this paper and carried out through a Dynamic Shear Rheometer (DSR) provides a comparison among mastics blended with different percentages of aged polymer modified bitumen, new virgin polymer modified bitumen and filler in terms of fatigue, self-healing and thixotropy. Data analysis is based on a model adopted in previous studies for polymer modified bitumens in order to calculate the fatigue endurance limit. Results show that the presence of increasing percentages of filler causes detrimental effects on mastic fatigue performance which can be offset by the addition of a certain amount of aged polymer modified bitumen. In fact, regardless of the filler content considered, a percentage of aged polymer modified bitumen (up to 45%) added to mastics enhances the fatigue endurance limit suggesting significant benefits when dealing with sustainable recycled mixtures containing Reclaimed Asphalt (RA) aggregates.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/241798 Collegamento a IRIS

2017
Effect of warm mix asphalt chemical additives on the mechanical performance of asphalt binders
MATERIALS AND STRUCTURES
Autore/i: FERROTTI, Gilda; DAVIDE, RAGNI; Lu, Xiaohu; CANESTRARI, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: Warm mix asphalt (WMA) has become very popular in asphalt pavement construction because it allows reducing both energy consumptions and carbon emissions.WMA can be obtained by using different types of additives and can be produced, applied, and compacted at temperatures 20–40 °C lower than hot mix asphalt. WMA additives allow reducing the working temperatures without compromising the final performance of the asphalt concrete. Many WMA additives are available on the worldwide market and some of them reduce the viscosity of asphalts binder (organic additives or foam) whereas others do not act on this sense (chemical additives). This study focuses on the effect of chemical additives on the performance of asphalt binders for WMA production. To this purpose, a neat bitumen, a polymer modified bitumen (PMB) and two different chemical additives were selected. All the binders were characterized through conventional tests, DSR, MSCR, FTIR and microscopic analysis. The result clearly showed that the influence of the chemical additives on the neat bitumen is negligible or non-existent. On the contrary, significant changes were observed in the modifiedbitumen properties. Specifically, chemical additives reduce the viscosity temperature susceptibility of PMBs in the temperature range between 80 and 140 °C, increase the rutting resistance potential and the elastic response of PMBs at high temperatures. Moreover, a morphological inspection supported the modifications observed in the rheological properties of PMBs.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/254765 Collegamento a IRIS

2017
Performance of warm recycled mixtures in field trial sections
Bearing Capacity of Roads, Railways and Airfields - Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields, BCRRA 2017
Autore/i: STIMILLI, ARIANNA; FRIGIO, FRANCESCA; CARDONE, Fabrizio; CANESTRARI, FRANCESCO
Editore: CRC Press/Balkema - Taylor & Francis Group
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Over the last decade, many researchers focalized on new technologies for the production of Warm Mix Asphalt (WMA) at lower temperatures to significantly reduce pollutant emissions and energy costs. Among various WMA technologies currently available on the market, chemical additives demonstrated to provide suitable performance with respect to the main distresses that typically affect flexible pavements. However, so far research efforts have mainly addressed the laboratory optimization of WMAs with rare correlations with field trials. The lack of experience about in-situ behavior risks limiting the use of such technologies, especially when mixtures include both Styrene-Butadiene-Styrene modified bitumens and Reclaimed Asphalt (RA). Given this background, the paper describes the performance evaluation of full-scale trial sections built with open and dense graded recycled WMAs as part of maintenance activities of an Italian motorway. Two segments included WMA mixtures prepared with different chemical additives, whereas a third segment was constructed with hot mixtures typically adopted in pavement rehabilitation works. Volumetric and stiffness properties, rutting and cracking resistance as well as interface shear strength were investigated on in-situ cored samples. Results showed that WMAs did not compromise mixture stiffness counterbalancing stiffening effects due to the presence of RA. Such a behavior resulted beneficial in terms of fracture resistance and did not penalize the rutting aptitude. Moreover, the shear strength evaluation showed that lower lay-down temperatures of WMAs did not alter the bond between pavement layers.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/250575 Collegamento a IRIS

2017
Time–temperature superposition principle for interlayer shear strength of bituminous pavements
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: GRAZIANI, Andrea; CANESTRARI, FRANCESCO; CARDONE, Fabrizio; FERROTTI, Gilda
Classificazione: 1 Contributo su Rivista
Abstract: Poor interlayer bonding leads to a reduction in service life of bituminous pavements, thus the identification and measurement of the parameters affecting interlayer shear strength (ISS) are becoming increasingly important. This study focuses on the effects of test temperature and interlayer deformation rate (IDR) on the ISS of double-layered asphalt concrete specimens, with the aim of comparing two different shear testing devices. Specifically, tests were performed by means of Ancona Shear Testing Research and Analysis and Leutner devices, at temperatures ranging from 5°C to 40°C and deformation rates ranging from 1 to 50 mm/min. Moreover, two interface conditions (with and without tack coat) were investigated. Experimental data showed that for both shear testing devices, higher IDR results in higher ISS, because of the time-dependent response of bituminous mixture and that the effect of IDR and temperature on ISS can be superposed allowing a master curve to be satisfactorily obtained using a three-parameter sigmoidal model.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/246527 Collegamento a IRIS

2017
Performance assessment of in plant produced warm recycled mixtures for open-graded wearing courses
TRANSPORTATION RESEARCH RECORD
Autore/i: FRIGIO, FRANCESCA; STIMILLI, ARIANNA; VIRGILI, AMEDEO; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Sustainable solutions, such as the combination of reclaimed asphalt pavement (RAP) as a partial substitution of virgin materials and warm-mix asphalt (WMA) additives to decrease production temperatures, represent the new research frontier in the asphalt industry. Specific investigations must evaluate the consequences of recycled WMA performance, especially in the case of open-graded (OG) mixtures, given that lower production temperatures can affect the adhesion properties and durability of those materials. This paper describes an experimental effort that involved OG mixtures produced in plant at warm temperatures (130çC) with two WMA chemical additives characterized by different compositions. In addition, an equivalent mixture (used as a control for comparison purposes) was produced at standard temperatures. Each material was prepared with a polymer-modified binder and 15% RAP. The main objective of the study was to characterize volumetric and mechanical properties of the investigated mixtures with particular attention paid to compactability aptitude and durability. To this end, gyratory-compacted specimens were subjected to several laboratory tests after dry and wet conditioning (i.e., indirect tensile strength, Cantabro test, semicircular bending, and repeated indirect tensile loading). Moreover, plant production of the investigated mixtures made it possible to evaluate the feasibility of large-scale processes. The WMA mixtures showed significant water susceptibility, although they guaranteed good compactability and satisfied mechanical acceptance requirements and international recommendations for raveling resistance in dry conditions. The chemical composition of the WMA additives was found essential to reduce the water damage. Surfactants and adhesion enhancers included within one of the investigated WMA additives ensured better water resistance than the other additive classified as a viscous regulator.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/245782 Collegamento a IRIS

2017
Mix design validation through performance-related analysis of in plant asphalt mixtures containing high RAP content
INTERNATIONAL JOURNAL OF PAVEMENT RESEARCH AND TECHNOLOGY
Autore/i: STIMILLI, ARIANNA; VIRGILI, AMEDEO; Giuliani, Felice; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Producing new asphalt mixtures with high content of Reclaimed Asphalt Pavement (RAP) is a major challenge in road construction for economic and environmental reasons. Although many laboratory studies addressed this issue, concerns related to the number of variables involved in the plant production process still limit hot recycling, especially when Styrene–Butadiene–Styrene (SBS) modified bitumens are used. In this sense, plant produced mixtures should be directly investigated to obtain reliable performance evaluations. Given this background, the paper proposes the mechanical characterization of dense-graded mixtures with 40% RAP produced at the asphalt plant as part of rehabilitation activities of an in-service motorway. The Bailey Method was applied to optimize the mix design. Mixtures were prepared by using two polymer modified bitumens (with high and low SBS polymer content) and selected RAP fractions composed only of asphalt layers including SBS modified bitumen itself. An additional mixture prepared according to the current practice for binder layers of motorway pavements was produced for comparison purposes. Advanced laboratory tests allowed the determination of the main material properties (i.e. compactability, cracking and rutting aptitude, indirect tensile strength, fatigue and self-healing). Results showed that mixtures with 40% RAP had performance comparable or even enhanced than the reference mixture especially when prepared with low modified bitumens. Consequently, this study shows that an accurate mix design and the selection of adequate bitumens overcome the potential drawbacks related to the use of high RAP percentage given the possibility to produce suitable recycled mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/245770 Collegamento a IRIS

2017
In-plant production of warm recycled mixtures produced with sbs modified bitumen: A case study
Transport Infrastructure and Systems - Proceedings of the AIIT International Congress on Transport Infrastructure and Systems, TIS 2017
Autore/i: Stimilli, A.; Frigio, F.; Canestrari, F.; Sciolette, S.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Asphalt mixtures produced at reduced temperatures through Warm Mix Additives (WMA) allow reductions of fuel consumption and harmful emissions, ensuring economic and environmental benefits. Considering that nowadays mixtures include more and more often reclaimed aggregates, the combination of recycling and WMA technologies represents a major challenge in road construction and needs further investigations for identifying drawbacks/advantages. Several concerns derive from regular in-plant productions since warm recycled mixtures have been mainly optimized through laboratory studies without evaluating possible issues of large-scale in-plant productions and lay-down processes. So far, few field constructions were realized, limited to small trial sections and without considering the use of modified bitumens. Given this background, the paper describes in-plant productions of warm recycled mixtures prepared with three chemical WMA additives for the construction of an extensive motorway segment. Dense-graded mixtures for binder and base courses as well as open-graded mixtures for wearing courses were produced. Three full-scale trial sections included warm mixtures whereas a further section, used as reference for comparison purposes, comprised analogous mixtures realized through hot recycling according to the current practice. The paper describes the construction steps and the controls carried out to verify technical standard requirements in terms of volumetric properties, compactability and Indirect Tensile Strength. The main objective was to attest the feasibility of large-scale productions to adequately reproduce the mix design previously implemented through laboratory studies when WMA technologies and recycling techniques are concurrently involved. Moreover, gas emissions monitoring at the asphalt plant during the real scale productions was conducted through Continuous Emissions Monitoring Systems in order to quantify the potential benefits in terms of pollution. Results demonstrate the suitability of WMA chemical additives to produce at low temperature mixtures with adequate performance, concurrently recording a significant reduction in pollutants without needing mix design modifications or implementation of expensive new technologies.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/264678 Collegamento a IRIS

2017
State of the art of tribological tests for bituminous binders
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: CANESTRARI, Francesco; INGRASSIA, LORENZO PAOLO; FERROTTI, Gilda; Lu, Xiaohu
Classificazione: 1 Contributo su Rivista
Abstract: Kinetic friction is a physical phenomenon which originates when two or more bodies are in contact and in relative motion, and causes energy consumption and wear. Lubricants are widely used in many fields to reduce kinetic friction and their behaviour is usually characterized through appropriate tribological tests. In fact, the science of tribology (from the Greek word “tribo” that means to rub and the Latin word “logia” that means study) investigates interactions between surfaces in relative motion. In the field of road materials, during asphalt mixing and compaction, bitumen acts similarly to lubricants, reducing friction between aggregates, and its lubricating properties significantly affect the energy required. According to recent studies, some Warm Mix Asphalt additives are able to reduce production and compaction temperatures (and therefore energy consumption) of asphalt mixtures by potentially improving the lubricating behaviour of the binder. Thus, tribological tests have recently been introduced in the investigation of bituminous binders to characterize their lubricating properties. This paper aims at providing the state of the art of tribological tests currently employed for the study of bituminous binders, as well as useful suggestions for improving these procedures. Since the introduction of such tests in the field of road materials is quite recent, an overview on tribology and tribological tests on common lubricants is presented, with the aim to highlight the main aspects to take into account when applying the tribological characterization of bituminous binders.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/254772 Collegamento a IRIS

2016
Adhesion properties of warm recycled mixtures produced with different WMA additives
Functional Pavement Design
Autore/i: FRIGIO, FRANCESCA; STIMILLI, ARIANNA; BOCCI, MAURIZIO; CANESTRARI, FRANCESCO
Editore: CRC Press, Taylor & Francis Group
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Eco-friendly, cost-saving and sustainable pavements have become a priority goal due to increased costs of raw materials and strict environmental regulations. To address these challenges, the use of Reclaimed Asphalt Pavements (RAP) and Warm Mix Asphalt (WMA) technologies is becoming more and more frequent in the asphalt industry. Adhesion properties and water susceptibility are major concerns associated with the use of WMA mixtures due to the reduced production temperatures that alter the interaction at the bi-tumen-aggregate interface. The materials response significantly varies depending on WMA technology as well as mixture type. In this sense, this study focused on the evaluation of both open and dense graded mixtures in-cluding RAP and three different WMA additives (organic wax, chemical additive and zeolite). Hot Mix Asphalt (HMA) mixtures were also prepared for comparison purposes. Since raveling (loss of aggregates from the surface layer) is strongly related to the adhesion properties between binder and aggregates, raveling performance were measured by means of Cantabro tests and correlated to the adhesion properties evaluated through Bond Bitumen Strength (BBS) tests. Tests were performed in dry and wet condition in order to assess the water susceptibility. Results showed that the type of WMA technology may influence mixture performance especial-ly when subjected to water conditioning. However, RAP aggregates within both open and dense graded WMA mixtures significantly limited the negative effects of reduced production tem-peratures in terms of adhesion and water resistance. Only the chemical WMA additive guaran-teed performance comparable to HMA, particularly in terms of water susceptibility.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/245773 Collegamento a IRIS

2016
Self-healing capability and thixotropy of bituminous mastics
INTERNATIONAL JOURNAL OF FATIGUE
Autore/i: MAZZONI, GIORGIA; STIMILLI, ARIANNA; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Fatigue resistance of bituminous materials is related to time-dependent phenomena, such as damage accumulation, hardening, viscoelasticity, thixotropy and healing. In bituminous mixtures, damage related to fatigue processes mainly involves bitumen and its combination with filler (i.e. mastic). Currently, there is no consolidated method for the determination of the fatigue endurance limit of bitumens that takes into account also the above-mentioned phenomena, while limited work has been done on mastics. To bridge this gap, the experimental investigation described in this paper provides a comparison between bitumens and corresponding mastics in terms of fatigue, self-healing and thixotropy. Long term aged materials were also taken into consideration in order to identify potential detrimental effects on self-healing due to oxidation phenomena, evaluating the possible inclusion of Reclaimed Asphalt (RA) for the production of bituminous mixtures. The data analysis was based on an innovative test method which had previously been implemented for bitumens and was carried out using a Dynamic Shear Rheometer (DSR). Moreover, the influence of morphological properties of filler on filler-bitumen interactions was assessed by means of a Scanning Electron Microscope (SEM). Results show that the above-mentioned analysis method is also suitable for analysing bituminous mastics and is able to identify the role of filler as well as the influence of ageing on the self-healing process of bituminous materials. The investigation confirms that a certain amount of aged bitumen added to a virgin bitumen/mastic is able to considerably improve the overall fatigue performance suggesting significant benefits when dealing with recycled mixtures including RA aggregates.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/238107 Collegamento a IRIS

2016
Shear failure characterization of time-temperature sensitive interfaces
MECHANICS OF TIME-DEPENDENT MATERIALS
Autore/i: CANESTRARI, FRANCESCO; FERROTTI, Gilda; GRAZIANI, Andrea
Classificazione: 1 Contributo su Rivista
Abstract: Poor interlayer bonding can lead to early failures and thus to a reduction in service life of bituminous pavements. For this reason, it is important to identify the parameters influencing the interlayer shear failure and to characterize their effect by means of laboratory test. In particular, this study is focussed on the effects of test temperature and deformation rate on the interlayer shear strength (ISS) of double-layered asphalt concrete specimens. First, the ISS was measured at temperatures ranging from 0 °C to 30 °C and deformation rates ranging from 0.5 mm/min to 9 mm/min using the Ancona Shear Testing Research and Analysis (ASTRA) device. Then the experimental data were analyzed using a two-stage statistical modelling approach. In the first stage, the variation of ISS versus deformation rate, at each testing temperature, was modelled using both a power-law and a logarithmic function. In the investigated range of deformation rate, the models allowed to estimate the mean ISS with residual standard error varying from 0.062 MPa to 0.128 MPa. Moreover, the linear regression coefficients, which measure the influence of the deformation rate on ISS, changed with temperature. In the second stage, both temperature and deformation rate were used as joint predictors of ISS by using an approach based on the superposition of their effects. Results showed that the time–temperature superposition approach is applicable and a sigmoid-shaped master curve for ISS was obtained. The proposed approach was validated by using ISS measurements obtained on the same materials with different test devices.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/238105 Collegamento a IRIS

2016
Influence of Specimen Dimension and Test Speed on the Shear Strength of Bituminous Interfaces
8th International RILEM Conference on Mechanisms of Cracking and Debonding in Pavements
Autore/i: ABUADDOUS, MUSAB; CANESTRARI, FRANCESCO; GRAZIANI, Andrea; FERROTTI, Gilda
Editore: A. Chabot; W.G. Buttlar; E.V. Dave; C. Petit; G. Tebaldi
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In view of the fact that pavements are multilayer systems, achieving high bonding between layers is a key element to increase service life. Interface debonding is mainly responsible for the slipping failure of pavements that leads to high rehabilitation and maintenance costs. The bonding between asphalt layers is usually evaluated by testing the interlayer shear strength and is affected by several parameters such as test speed, test temperature, normal stress applied and specimen diameter. This paper focuses on the effect of test speed and specimen diameter on the shear strength evaluated through the Leutner equipment, for a typical dense graded asphalt mixture. Leutner tests were carried out on double-layered specimens with a diameter of 100 and 150 mm and with interlayer deformation rates corresponding to nominal test speeds of 1, 2.5, 5, 10, 25 mm/min. The effective interlayer deformation rate was calculated by measuring the deformation through an external transducer in order to perform a reliable data analysis. Results showed a steady increase in the shear strength with the increase in the interlayer deformation rate. Moreover, a clear scale effect was observed at any test speed resulting in higher values for shear strength measured on specimens with diameter of 100 mm.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/238119 Collegamento a IRIS

2016
Fracture characterization of grid-reinforced asphalt pavements
8th RILEM International Conference on Mechanisms of Cracking and Debonding in Pavements
Autore/i: Graziani, Andrea; Sangiorgi, Cesare; Canestrari, Francesco
Editore: A. Chabot; W.G. Buttlar; E.V. Dave; C. Petit; G. Tebaldi
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The ability of grid-reinforced asphalt systems to improve pavement performance depends on the selection of the appropriate reinforcement product. In particular, the flexural properties of reinforced double-layered asphalt systems can be used to investigate the potential benefits produced by an interlayer reinforcement. This paper presents the results of monotonic three-point bending tests on grid reinforced double-layered asphalt specimens carried out as part of an interlaboratory test organized by the TG4 of RILEM TC 237-SIB focused on the evaluation of pavement grid effects on both flexural strength and interlayer bonding of asphalt pavements. The tests were carried out on beams of different geometry, at different test temperatures and speeds. Results were analyzed in terms of fracture work and by considering energy-based dimensionless indices, which allowed the direct comparison of apparently different bending test procedures. Results showed that grid reinforcement did not noticeably influence the crack-initiation toughness. However, the fracture energy was clearly influenced by the grid presence and by the grid type. This effect was related to the effect on the post-peak deformation phase and to the different failure mechanisms.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/238120 Collegamento a IRIS

2016
Aging effects on recycled WMA porous asphalt mixtures
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: FRIGIO, FRANCESCA; Raschia, Simone; Steiner, Daniel; Hofko, Bernhard; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Nowadays, the use of reclaimed asphalt pavements (RAP) is often combined with Warm Mix Asphalt (WMA) technologies with several benefits in terms of environment, cost and mechanical performance. Concerns still exist related to in-service and aging characteristics of warm recycled mixtures since WMA technologies have been developed over the last decade and hence long term performance data are not available yet. The objective of this experimental study is to evaluate the aging effect on recycled porous asphalt (PA) mixtures produced at reduced temperatures using different WMA additives (organic, chemical and zeolite) and including 15% of RAP. In this sense, long term aging was simulated in the laboratory on compacted specimens by means of the Viennese Aging Procedure (VAPro). Rheological properties of the extracted bitumen samples were measured in order to evaluate possible links between bitumen and mixtures performance. As far as mixtures are concerned, stiffness tests were carried out before and after aging, whereas fatigue resistance was evaluated on long term aged mixtures to compare long term performance of HMA and WMA porous asphalt. Mixtures as well as bitumens results showed that the lower aging process that WMA mixtures undergo during production affects mixtures stiffness at the beginning of service life. Only the presence of the organic additive increases the stiffness of WMA bitumens and mixtures due to the crystalline network structure that forms in the bitumen. On the other hand, extensive long term aging effects were measured in case of WMA mixtures. Nonetheless, overall fatigue results showed that long term fatigue performance of WMA mixtures are not significantly affected compared to HMA regardless of WMA additive types.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/238108 Collegamento a IRIS

2016
In plant production of hot recycled mixtures with high reclaimed asphalt pavement content: A performance evaluation
8th RILEM International Symposium on Testing and Characterization of Sustainable and Innovative Bituminous Materials
Autore/i: STIMILLI, ARIANNA; VIRGILI, AMEDEO; Giuliani, Felice; CANESTRARI, FRANCESCO
Editore: Kluwer Academic Publishers
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Nevertheless hot recycling process is nowadays a widespread technique, many doubts related to the in plant recycling process effects on the performance of recycled mixtures still exist and limit the maximum allowable amount of Reclaimed Asphalt Pavement (RAP). Therefore, the feasibility of an efficient production of plant hot recycled mixtures characterized by high RAP content and suitable performance should be properly addressed. To this aim, the overall performance of hot recycled asphalt mixtures produced in asphalt plant and containing high RAP content were assessed in this study. The mixtures were prepared with two different bitumens (high and low content of SBS polymer modifier) and 40 % of RAP only deriving from asphalt layers containing polymer modified bitumens. The aggregate grading curve was previously optimized through a specific laboratory study by applying the Bailey Method and using selected RAP. A third mixture, currently used for binder layers in motorway pavements, was also studied for comparative purposes. Compactability, stiffness, cracking and rutting resistance and fatigue behavior were investigated. Results of the mechanical tests suggest that mixtures containing 40 % RAP are suitable for the production of new asphalt pavements, especially when low modified bitumens are used. In fact, the performance of such mixtures were comparable or even higher than those of the reference mixture. In particular, the specific and accurate mix design allowed the potential drawbacks due to higher RAP content to be balanced.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232974 Collegamento a IRIS

2016
Inter-laboratory shear evaluation of reinforced bituminous interfaces
8th RILEM International Symposium on Testing and Characterization of Sustainable and Innovative Bituminous Materials
Autore/i: FERROTTI, Gilda; D’Andrea, Antonio; Maliszewski, Maciej; Partl, Manfred Norbert; Raab, Christiane; Sangiorgi, Cesare; CANESTRARI, FRANCESCO
Editore: Kluwer Academic Publishers
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Over the last decades, the use of grids between asphalt layers has been gaining interest. Several test methods have been proposed in order to simulate the complex mechanical behavior of reinforced pavements and to assist practitioners in the selection of the appropriate reinforcement product. For this purpose, the Task Group 4 (Pavement Multilayer System Testing) of the RILEM technical committee TC 237-SIB (Testing and Characterization of Sustainable Innovative Bituminous Materials and Systems) organized an inter-laboratory experiment, constructing one trial test section to obtain double-layered asphalt pavement samples for the participating laboratories. The experiment placed two grid types (a glass fiber reinforced polymer grid and a carbon fiber/glass fiber pre-bituminised grid) between two asphalt layers, thereby creating two reinforced double-layered systems. As a control, an unreinforced interface was also realized. This paper presents the overall results of interlayer shear tests carried out by five participating laboratories using five different shear testing methodologies. The objective is to show the effect of two grid types on the shear behaviour of reinforced double-layered systems and to compare the findings which emerged from using different test devices and methods under different testing conditions (e.g. sample geometry, temperature, loading time, normal stress). Consistent and reliable results have been obtained through the various methodologies adopted. It has been observed that grid-reinforced samples provide lower interlayer shear strength compared with unreinforced samples. Glass-fiber grid system, which is of greater thickness and greater torsional stiffness, displayed less shear strength than carbon fiber/glass fiber-reinforced grid systems.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232937 Collegamento a IRIS

2016
Effect of warm mix chemical additives on the binder-aggregate bond strength and high-service temperature performance of asphalt mixes containing electric arc furnace steel slag
8th RILEM International Symposium on Testing and Characterization of Sustainable and Innovative Bituminous Materials
Autore/i: Pasetto, Marco; Giacomello, Giovanni; Pasquini, Emiliano; CANESTRARI, FRANCESCO
Editore: Kluwer Academic Publishers
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Warm Mix Asphalt (WMA) is a modified asphalt concrete, obtained by using organic, chemical or foaming additives, which can be produced and compacted at lower temperatures (100-140 °C). The environmental sustainability of WMA can be enhanced with the inclusion of steel slag in substitution of natural aggregates. Given this background, this paper illustrates an experimental research aimed at characterizing WMA containing steel slag. Rheological tests were carried out on asphalt binders in order to investigate the effect of the WMA additive on high-service temperature properties. Then, the bond strength between asphalt binders and aggregates (limestone and steel slag) was investigated. Finally, compactability and permanent deformation resistance of the studied mixtures were also evaluated. Results mainly showed that, regardless the presence of steel slag, the studied additive allowed adequate mixing and compaction at lower temperatures, improving the bond strength between binder and aggregates without affecting permanent deformation resistance of asphalt mixes.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232971 Collegamento a IRIS

2016
Geocomposite-reinforcement of polymer-modified asphalt systems
8th RILEM International Symposium on Testing and Characterization of Sustainable and Innovative Bituminous Materials
Autore/i: CANESTRARI, FRANCESCO; FERROTTI, Gilda; ABUADDOUS, MUSAB; Pasquini, Emiliano
Editore: Kluwer Academic Publishers
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Geosynthetic reinforcement has proven to be an effective method to improve road pavement performance. In this regard, composite materials obtained combining bituminous membranes with reinforcing grids represent a promising option thanks to the waterproofing and stress-relieving effect produced by the membrane and the enhanced mechanical characteristics provided by the grid. This research had the objective of evaluating the effectiveness of pavement rehabilitation by means of an optimized composite material, consisting of an elastomeric bituminous membrane reinforced with a fiberglass grid, applied at the interface of a polymer-modified asphalt system. An unreinforced reference configuration was also investigated for comparison purpose. Interlayer shear tests and three-point bending tests were performed on double-layered specimens in order to evaluate bond strength at the interface and toughness (i.e. fracture resistance) of the pavement system, respectively. Shear tests showed that the reinforcement at the interface reduces the bonding between asphalt layers even if a residual cohesion contribution is provided after shear failure. As far as flexural properties are concerned, the real contribution of the reinforcement consists in the delay of crack propagation rather than in the inhibition of crack initiation.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232970 Collegamento a IRIS

2015
Validation of a hydraulic model to prevent emulsion flowing in chip sealing
INTERNATIONAL JOURNAL OF PAVEMENT RESEARCH AND TECHNOLOGY
Autore/i: Giuliani, Felice; FERROTTI, Gilda; Montepara, Antonio; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Chip sealing is a pavement surface treatment that consists in the application of an asphalt binder (bitumen or bituminous emulsion) on an existing pavement followed by the spreading of aggregate chips and by the rolling of the surface, in order to embed the aggregate into the binder. This treatment is typically used as preventive maintenance technique of asphalt pavements, in order to seal fine cracks and improve skid-resistance of road surfaces. Moreover, chip sealing is often employed on rural roads, that carry low traffic volumes and are often characterized by critical conditions such as small radius of curvature and/or high longitudinal slopes. In the latter case, the application of the bituminous emulsion becomes a crucial concern as an excessive flowing of the bitumen could take place due to the high pavement slope and its spreading could become not uniform. In order to investigate these aspects, in this study ahydraulic model of the theoretical flow of bituminous emulsions on high longitudinal slope road surfaces was proposed and validated through a laboratory experimental investigation. To this aim, an original laboratory equipment (Chip Seal Laboratory Simulator), that allows the simulation of the most critical conditions during field activities, was properly designed and realized. The theoretical analysis and the experimental validation suggested practical recommendations in terms of longitudinal working speeds in critical contexts, very usual in practice.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232924 Collegamento a IRIS

2015
Innovative testing protocol for the evaluation of binder-reclaimed aggregate bond strength
TRANSPORTATION RESEARCH RECORD
Autore/i: CANESTRARI, Francesco; FERROTTI, Gilda; CARDONE, Fabrizio; STIMILLI, ARIANNA
Classificazione: 1 Contributo su Rivista
Abstract: The durability of asphalt mixtures is strongly related to the adhesion properties developed at the interface between binder and aggregates. The loss of adhesion implies a rapid deterioration (e.g. stripping, raveling) of pavement layers under traffic loads, especially when the pavement is affected by the presence of moisture. Adhesion is a complex phenomenon related to the mineralogical and morphological nature of aggregates, as well as to the chemical binder composition and the environmental conditions. Nowadays, its evaluation becomes even more complicated as an increasing percentage of Reclaimed Asphalt is used in the production of new asphalt mixes. Therefore, adhesion properties are also related to the mechanisms developed at the interface between virgin binder and aged binder that coats the Reclaimed Asphalt aggregate surface. An innovative procedure to evaluate the compatibility of the system virgin binder/Reclaimed Asphalt aggregate is proposed in this study. This procedure allows to simulate in laboratory the substrate of a Reclaimed Asphalt aggregate and can integrate the Binder Bond Strength test currently used to investigate bonding properties and water sensitivity of the system binder-virgin aggregates. Tests were conducted using different aggregate sources, several modified binders and two conditioning types (dry, wet). It was found that this procedure is able to catch the differences between different test configurations and variables. In particular, the artificial reclaimed aggregate substrate ensured higher adhesion performance compared to the virgin aggregate, especially in wet condition, regardless the modification level of the virgin bitumen adopted.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/149303 Collegamento a IRIS

2015
Laboratory study to evaluate the influence of reclaimed asphalt content on performance of recycled porous asphalt
JOURNAL OF TESTING AND EVALUATION
Autore/i: FRIGIO, FRANCESCA; Pasquini, Emiliano; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Road-pavement maintenance and rehabilitation are more frequently performed on porous asphalt (PA) surface layers because of their inherent low durability. Such activities lead to the production of a considerable amount of reclaimed asphalt (RA), mainly from PA layers and from the heavy use of virgin non-renewable natural resources, because of the fact that the use of RA is not usually allowed in PA. In this sense, the use of milled materials from old PA wearing courses in new PA layers promotes an important cycle of re-use that should be encouraged. The experimental study aims to investigate the performance of recycled PA mixtures prepared by partly substituting virgin aggregates with selected coarse RA from a milled PA wearing course. A reference PA mixture (without RA) and six recycled PA mixtures prepared with two amounts of RA (20 % and 25 %) and three total binder contents (5.25 %, 5.50 %, and 5.75 %) were investigated in terms of compactability, durability, and water resistance. In this sense, indirect tensile strength (ITS) tests, particle loss (Cantabro) tests, semicircular bending (SCB) tests, and repeated indirect tensile tests were carried out in both dry and wet conditions. Moreover, compactability properties of the reference PA mixture and the recycled PA mixtures were compared. Results showed that recycled PA mixtures with 20 % and 25 % of RA can perform as well as the reference PA mixture in terms of moisture resistance and durability if an accurate mix design is performed. The optimum total binder content was found to increase as the amount of RA increases, because of the fact that a prominent part of the aged binder acts as “black aggregate.” Finally, on the basis of a performance-based equivalence principle, a reliable approach for a practical method able to predict the amount of “re-activated” binder within the RA is proposed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/224127 Collegamento a IRIS

2015
New method to estimate the “re-activated” binder amount in recycled hot-mix asphalt
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: STIMILLI, ARIANNA; VIRGILI, AMEDEO; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: The magnitude of the binder re-activation within the reclaimed asphalt pavement (RAP) fraction is a major concern when recycled hot-mix asphalt (HMA) is produced, since it directly affects the final performance of the mix. Currently, no reliable methods to predict the RAP binder re-activation are available and the lack of such information prevents the quantification of the proper amount of virgin binder to be added to the recycled HMA.This study proposes a new method to estimate the re-activated binder amount based on the surface area (SA) of RAP aggregates. Laboratory results demonstrated the effectiveness of the SA approach in the case of RAP amounts typically used for hot-recycled HMA. Moreover, the experimental investigation suggested that revised coefficients are needed for the evaluation of the SA to account for the presence of clumps when high amounts of fine RAP aggregates are used.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232925 Collegamento a IRIS

2015
Shear and flexural characterization of grid-reinforced asphalt pavements and relation with field distress evolution
MATERIALS AND STRUCTURES
Autore/i: CANESTRARI, FRANCESCO; Belogi, Leonello; FERROTTI, Gilda; GRAZIANI, Andrea
Classificazione: 1 Contributo su Rivista
Abstract: The use of geogrids at the interface of asphalt layers is currently adopted to improve pavement performance in terms of rutting, fatigue and reflective cracking. Several test methods have been proposed in order to simulate the complex mechanical behavior of reinforced pavements and assist practitioners in the selection of the appropriate reinforcement product. A particular subject of debate is the evaluation of geogrid effects in terms of both flexural strength and interlayer bonding. In this context, an interlaboratory experiment has been organized as part of the RILEM TC 237-SIB/TG4 with a twofold objective: to compare the predictive effectiveness of different experimental approaches and to analyze the behavior of different geogrid types. For this purpose two experimental reinforced test sections have been realized, the first one to prepare samples for the interlaboratory experiment, the second one to analyze the geogrid field performance under heavy traffic conditions. This paper describes the test results obtained by one participating laboratory on double-layered asphalt samples extracted from the first experimental section and compares them with the periodic visual observation of the reflective cracking evolution occurred in the second test section. The laboratory tests were performed following a specific testing protocol that combines interlayer shear tests, repeated loading tests in a four-point bending configuration and quasi-static three-point bending tests, in order to investigate the overall performance of double-layered asphalt systems. Results have shown that geogrid reinforcement does not noticeably influence the flexural stiffness and strength in the pre-cracking phase, whereas the crack propagation speed can be significantly reduced and the failure behavior may change from quasibrittle to ductile, depending on the interlayer shear resistance. Laboratory results were confirmed by periodic visual observation of field performance in terms of reflective cracking evolution.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/127272 Collegamento a IRIS

2015
Modeling and assessment of self-healing and thixotropy properties for SBS modified binders
INTERNATIONAL JOURNAL OF FATIGUE
Autore/i: CANESTRARI, FRANCESCO; VIRGILI, AMEDEO; GRAZIANI, Andrea; STIMILLI, ARIANNA
Classificazione: 1 Contributo su Rivista
Abstract: The fatigue endurance limit of binders is the results of more phenomena (e.g. viscoelasticity, damage, healing, thixotropy, steric hardening) that interact simultaneously making the mechanisms behind the fatigue behavior not properly understood. Currently, there is no consolidated analytical approach inclusive of such phenomena to characterize fatigue performance. This research proposes a criterion to determine the fatigue resistance of binders subjected to monotonous cyclic loading with multiple rest periods. The main rheological properties are measured during each stage using a Dynamic Shear Rheometer and the modeling of their evolution is proposed. The experimental program includes different binders in order to investigate the effects of SBS modification levels and aged binder contents on self-healing potential and fatigue behavior. The proposed criterion enables to identify fundamental contributions leading to a comprehensive fatigue endurance limit. This approach allows different binders to be distinguished taking into account their self-healing capacity and can help to establish a better correlation with in-service performance of mixtures. Moreover, a comparison with a previous analytical approach based on the same kind of test (time sweep) with only one rest period is proposed in order to evaluate the effectiveness and reliability of the proposed criterion. Results show that multiple rest periods are needed in order to fully understand the self-healing and fatigue behavior of bituminous binders and to quantify the contributions given by thixotropy. © 2014 Elsevier Ltd. All rights reserved.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/224126 Collegamento a IRIS

2015
Mechanical 3D characterization of epoxy asphalt concrete for pavement layers of orthotropic steel decks
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Bocci, E.; GRAZIANI, Andrea; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Epoxy asphalt has been used for over 40 years to pave orthotropic steel deck bridges. However, few investigations have aimed at evaluating and modelling its rheological behaviour. The present paper deals with the three dimensional viscoelastic characterization of epoxy asphalt concrete (EAC) in the frequency domain, focusing on the complex Young's modulus and the complex Poisson's ratio. Cyclic compression tests were performed on cylindrical specimens, providing the measurement of axial and transverse strains. A conventional frequency sweep procedure was followed for different test temperatures. In addition, ordinary hot mix asphalt (HMA) specimens were tested as reference. The time-temperature superposition principle and the Huet-Sayegh rheological model were used to analyse the experimental data. Indirect tensile strength and water sensitivity were also evaluated. Results showed that EAC had higher stiffness and thermal sensitivity with respect to HMA. The complex Poisson's ratio of both EAC and HMA was found to be dependent on temperature and frequency: absolute value ranged from 0.30 to 0.42 and from 0.27 to 0.45, respectively, while the phase angles were lower than 5°.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/224128 Collegamento a IRIS

2015
Influence of mineral fillers on the rheological response of polymer-modified bitumens and mastics
JOURNAL OF TRAFFIC AND TRANSPORTATION ENGINEERING
Autore/i: Cardone, Fabrizio; Francesca, Frigio; Ferrotti, Gilda; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: The rheological properties of the bituminous components (bitumen and bituminous mastic) within asphalt mixtures contribute significantly to the major distresses of flexible pavements (i.e. rutting, fatigue and low temperature cracking). Asphalt mixtures are usually composed of mastic-coated aggregates rather than pure bitumen-coated aggregates. The purpose of this study is to investigate the effects of mineral fillers on the rheological behaviour of several polymer-modified bitumens (PMBs) through laboratory mixing. A neat bitumen and two types of polymers (elastomeric and plastomeric) were used to produce PMBs, and two fillers with different minerals (limestone and basalt) were selected to obtain mastics. The dynamic shear rheometer (DSR) and bending beam rheometer (BBR) were used to characterize the rheological properties of PMBs and mastics. In particular, multiple stress creep recovery (MSCR) tests were performed to evaluate the rutting potential at high temperatures, whereas BBR tests were carried out to investigate the low temperature behaviour of these materials. BBR results for unmodified mastics show that the increase of stiffness is similar regardless of the filler type, whereas results for polymer-modified mastics indicate that the degree of stiffening depends on the combination of filler/polymer types. MSCR results show that adding filler leads to a reduced susceptibility of permanent deformation and an enhanced elastic response, depending on the combination of filler/polymer types. Overall results suggest that a physicalechemical interaction between the filler and bitumen occurs, and that the interaction level is highly dependent on the type of polymer modification.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/228649 Collegamento a IRIS

2015
Use of reclaimed asphalt in porous asphalt mixtures: laboratory and field evaluations
JOURNAL OF MATERIALS IN CIVIL ENGINEERING
Autore/i: FRIGIO, FRANCESCA; Pasquini, Emiliano; Partl, Manfred N.; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Maintenance and reconstruction of road pavements involve the production of huge amount of discarded material, such as reclaimed asphalt (RA), every year. As a consequence, issues related to RA stockpiles and disposals are dramatically increasing. At the same time, the growing importance of environmental and economic matters has led researchers and engineers to promote reusing milled materials rather than using valuable and nonrenewable natural resources (bitumen and aggregates). Road pavement maintenance and construction usually involve the use of porous asphalt (PA) mixtures, in particular in the case of motorways and highways. In fact, PA mixtures are widely employed as pavement surface layer thanks to their ability in reducing traffic noise and enhancing safety in wet conditions. In this sense, the reuse of RA into PA should be strongly encouraged. Unfortunately, technical specifications adopted in many countries do not allow any recycled materials in porous asphalt surface layers yet. Thus, reliable techniques allowing the use of RA in new PA mixtures are needed. In this research study, the use of coarse RA from old PA as aggregate in new PA mixtures was evaluated. Because a previous laboratory study demonstrated that the use of 15% of RA aggregates in PA mixtures seems possible (or even recommendable) as long as an accurate mix design with adequate binder contents is performed, new laboratory and field evaluations on recycled PA mixtures with15% of RA aggregates were carried out. On one hand, cyclic coaxial shear tests (CASTs) were performed under both dry and water-submerged conditions in order to evaluate the simultaneous effect of traffic and water exposure. On the other hand, a comprehensive laboratory experimental program for assessing acceptability, durability, fracture resistance, and water sensitivity was carried out on materials taken from the field during the construction of a full-scale trial section. Moreover, drainage properties of surface layers were measured along such a trial section. Overall test results demonstrated that including 15% of selected coarse recycled aggregates into porous asphalt mixtures does not compromise performances and durability of both asphalt-plant and laboratory produced mixtures. It was demonstrated that recycled mixture with 5.25% of total binder content and prepared by accurate mix design can perform as well as (or even better than) standard PA mixture in terms of workability, acceptability, abrasion resistance, repeated loading resistance, fracture propagation resistance, moisture sensitivity, and water drainability.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/223746 Collegamento a IRIS

2015
Performance evaluation of hot recycled mixtures containing sbs modified binder
Bituminous Mixtures and Pavements VI - Proceedings of the 6th International Conference on Bituminous Mixtures and Pavements, ICONFBMP 2015
Autore/i: STIMILLI, ARIANNA; FERROTTI, Gilda; Radicioni, Daniele; CANESTRARI, FRANCESCO
Editore: CRC Press/Balkema
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Over the last decades, Reclaimed Asphalt Pavement (RAP) has become one of the most recycled materials. Currently, RAP is mainly used for unbound layers, without exploiting the replacement of a portion of the more expensive virgin binder. Moreover, the increasing quantity of RAP which includes aged modified binders complicates material analysis. This paper presents a laboratory mechanical investigation on hot recycled mixtures prepared with RAP including aged Styrene-Butadiene-Styrene (SBS) modified binder. A reference mixture with 25% RAP and four mixtures with 40% RAP were investigated. Two total binder contents and two virgin SBS modified binders were used to produce mixtures with 40% RAP, which were designed using the Bailey method. Compactibility, stiffness properties, cracking and rutting resistance were evaluated on laboratory compacted specimens. Results suggest that amounts of RAP up to 40% are suitable for the production of new bituminous materials, when a specific and detailed mix design is performed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232927 Collegamento a IRIS

2015
Low-temperature mechanics of hot recycled mixtures through Asphalt Thermal Cracking Analyzer (ATCA)
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: STIMILLI, ARIANNA; CANESTRARI, FRANCESCO; Teymourpour, P.; Bahia, H. U.
Classificazione: 1 Contributo su Rivista
Abstract: Thermal cracking is recognized as a critical failure mode for bituminous mixtures and good fracture properties are a key factor to obtain long lasting asphalt pavements in cold climate. Investigating this aspect in hot recycled mixtures with high amount of Reclaimed Asphalt Pavement (RAP) is fundamental due to the stiffening effect of aged bitumen that can emphasize the cracking aptitude of the mixture when subjected to thermal stresses. An innovative tool for characterizing the low-temperature cracking behavior of asphalt mixtures is the new developed Asphalt Thermal Cracking Analyzer (ATCA). It allows the evaluation of several parameters (e.g. glass transition temperature, coefficients of contraction, cracking temperature) directly related to the mechanics of low-temperature performance. In this study, four recycled asphalt mixtures were produced in laboratory with 40% of RAP using the Bailey Method as tool to optimize the aggregate structure. Different binder contents and modified bitumens (with various level of polymer modification) were employed. An additional mixture with 25% of RAP was used as control mixture. All the mixes were tested using the ATCA device. Moreover, an original image analysis was performed to assess at a microscale level the effects of compaction properties and aggregate structure on thermal cracking response. Results show that mixtures with 40% of RAP can behave better than the control mixture at low temperature if an accurate mix design is performed. Careful selection of RAP material and type and quantity of virgin bitumen can enhance low temperature performance and aggregate packing although high amount of RAP aggregates.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/224129 Collegamento a IRIS

2015
Laboratory evaluation of the effect of low-temperature application of warm-mix asphalts on interface shear strength
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Pasquini, Emiliano; Giacomello, Giovanni; Pasetto, Marco; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: A potential drawback, not yet investigated, of low application temperatures of asphalt mixes could be a reduced interface shear strength. Such low temperatures could be due to improper construction as well as to the use of warm mix asphalt (WMA) technology. In this sense, this paper illustrates an experimental laboratory research aimed at characterizing interface shear properties of double-layered asphalt systems. The upper layer of the specimens (WMA or hot mix asphalt control mix) was mixed and compacted at different temperatures in order to simulate different application conditions. A plain bitumen and a polymer modified binder were used for the asphalt mixes whereas an organic (wax) additive was selected as warm modifier. Experimental data were also compared with the stress field of a typical flexible pavement calculated through a layered elastic theory (LET) model. The research study mainly showed that interface shear strength sensibly decreases for low application temperatures of the upper layer (below 140 °C) regardless of bitumen type and presence of the warm additive. However, the use of polymer modified bitumen as binder for the upper layer asphalt concrete leads to noticeably higher interface shear strength at any test temperature reducing the risk of delamination.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232910 Collegamento a IRIS

2015
Geocomposites against reflective cracking in asphalt pavements: laboratory simulation of a field application
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Pasquini, Emiliano; Pasetto, Marco; CANESTRARI, FRANCESCO
Classificazione: 1 Contributo su Rivista
Abstract: Asphalt pavements often suffer reflective cracking phenomena. Crack appearance at the road surface leads to several detrimental effects, including the loss of watertightness. Geocomposites, such as grid-reinforced bituminous membranes, represent an efficient method against reflective cracking since they combine improved tensile properties of grids and stress-relieving effects of membranes. Moreover, membranes allow pavement waterproofing. This paper presents laboratory and field studies carried out to investigate the reflective cracking resistance of geocomposite-reinforced asphalt systems. The study is based on a real-scale field trial constructed along an in-service motorway. Five geocomposites were taken into account and the possible use of a tack coat and application on a milled surface were also evaluated. Interface shear tests were carried out both on field cores and on laboratory-made samples. Moreover, pre-notched laboratory specimens were subjected to specifically developed simulative tests through the Wheel Tracking equipment. Experimental results clearly showed that a proper selection and application of optimised grid-reinforced bituminous membranes can significantly enhance reflective cracking resistance of asphalt pavements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232911 Collegamento a IRIS

2015
Pseudo-variables method to calculate HMA relaxation modulus through low-temperature induced stress and strain
MATERIALS & DESIGN
Autore/i: CANESTRARI, FRANCESCO; STIMILLI, ARIANNA; Bahia, Hussain U.; VIRGILI, AMEDEO
Classificazione: 1 Contributo su Rivista
Abstract: Thermal cracking is a critical failure mode for asphalt pavements. Relaxation modulus is the major viscoelastic property that controls the development of thermally induced tensile stresses. Therefore, accurate determination of the relaxation modulus is fundamental for designing long lasting pavements. This paper proposes a reliable analytical solution for constructing the relaxation modulus master curve by measuring stress and strain thermally induced in asphalt mixtures. The solution, based on Boltzmann's Superposition Principle and pseudo-variables concepts, accounts for time and temperature dependency of bituminous materials modulus, avoiding complex integral transformations. The applicability of the solution is demonstrated by testing a reference mixture using the Asphalt Thermal Cracking Analyzer (ATCA) device. By applying thermal loadings on restrained and unrestrained asphalt beams, ATCA allows the determination of several parameters, but is still unable to provide reliable estimations of relaxation properties. Without them the measurements from ATCA cannot be used in modeling of pavement behavior. Thus, the proposed solution successfully integrates ATCA experimental data. The same methodology can be applied to all test methods that concurrently measure stress and strain. The statistical parameters used to evaluate the goodness of fit show optimum correlation between theoretical and experimental results, demonstrating the accuracy of this mathematical approach.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/225311 Collegamento a IRIS

2015
Field validation of hot-recycled porous asphalt containing 20% rap
Bituminous Mixtures and Pavements VI - Proceedings of the 6th International Conference on Bituminous Mixtures and Pavements, ICONFBMP 2015
Autore/i: FRIGIO, FRANCESCA; Pasquini, Emiliano; CANESTRARI, FRANCESCO
Editore: CRC Press/Balkema
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The capability of reducing traffic noise and enhancing safety in wet conditions makes Porous Asphalt (PA) mixtures as one of the most common surface layers for road pavements. Thus, the use of Reclaimed Asphalt Pavement (RAP) in PA mixtures can lead to important economic and environmental benefits that should be strongly encouraged. However, most technical specifications do not allow such use of yet due to the inherent low durability and high air void content of PA mixtures. In this sense, reliable techniques allowing the use of RAP in PA mixtures are needed. In this research, the possible use of 20% of coarse fraction of RAP obtained from old PA surface layers in new PA mixtures was evaluated. A comprehensive laboratory and field study was carried out based on the construction of a full scale trial section. Results showed that recycled PA mixtures were able to outperform standard PA mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/232926 Collegamento a IRIS

2014
Advanced Characterization of Clear Chip Seals
JOURNAL OF TESTING AND EVALUATION
Autore/i: Pasquini E.; Bonati A.; Giuliani F.; Canestrari F.
Classificazione: 1 Contributo su Rivista
Abstract: Chip seals are widely used throughout the world for the construction and preventive maintenance of asphalt pavements because they are recognized as cost-effective solutions able to improve skid resistance while creating a waterproof surface. On the other hand, chip seals are often affected by early stone loss because of several, not always easily manageable, material-related and traffic-related factors. It is, therefore, in the interest of researchers to develop scientific methods able to predict the aggregate retention performance of chip seals. Given this background, in the present paper, a performance-based evaluation of chip seals with regard to aggregate retention properties is carried out through a laboratory test based on the Ancona shear testing research and analysis equipment. In this study, a chip seal prepared with a clear emulsion derived by emulsifying a synthetic clear binder was analyzed and compared with two traditional chip seals manufactured with a plain cationic bituminous emulsion and a styrene butadiene styrene polymer-modified asphalt emulsion, respectively. Specifically, six chip seals obtained by combining the three selected emulsions with two types of aggregates (crushed limestone and basalt) were tested at three different temperatures. Moreover, a rheological characterization of emulsion residues was also carried out through the dynamic shear rheometer and the binder bond strength adhesion tester. Results mainly showed that the investigated clear synthetic emulsion can be successfully used for the construction of clear chip seals in combination with aggregates of different mineralogy.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/223740 Collegamento a IRIS

2014
Structural response of grid-reinforced bituminous pavements
MATERIALS AND STRUCTURES
Autore/i: Andrea Graziani; Emiliano Pasquini; Gilda Ferrotti; Amedeo Virgili; Francesco Canestrari
Classificazione: 1 Contributo su Rivista
Abstract: Grid reinforcement is becoming a standard construction and rehabilitation technique to improve the performance of bituminous pavements. Currently, selection of the appropriate grid type and position is based on empirical criteria or derived from the results of laboratory tests which consider a single aspect of the mechanical behavior of the grid-reinforced systems. An improvement in the existing design and testing approaches could be obtained considering the actual response of grid-reinforced systems under vehicular loads. An instrumented pavement section was constructed to achieve this objective by installing a glass fiber polymer grid (FP) and a carbon fiber/glass fiber grid (CF) inside a double-layered asphalt surfacing along an in-service road. This pavement is part of a wider project which also involves a RILEM inter-laboratory test on the same reinforced systems. The pavement response to falling weight deflectometer (FWD) and real-scale truck loads was measured using pressure cells and asphalt strain gauges installed inside the pavement. A layered elastic theory (LET) model was adopted to perform both back-calculation of layer moduli and forward-calculation (simulation) of pavement stress and strain. The FWD and the real-scale tests yielded congruent results highlighting that the strain field inside the double-layered surfacing was considerably reduced by the installation of the CF/glass fiber grid whereas the glass FP grid was probably too stiff, potentially leading to interface debonding. The LET model proved to be a simple and effective tool for a first-approach analysis of the reinforcement pavement response.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/150303 Collegamento a IRIS

2014
Influence of polymer modification on asphalt binder dynamic and steady flow viscosities
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Cardone F.; Ferrotti G.; Frigio F.; Canestrari F.
Classificazione: 1 Contributo su Rivista
Abstract: Asphalt pavement performance such as rutting, crack initiation and propagation as well as fatigue behaviour are substantially affected by the rheological properties of the bitumen. In this sense, the use of polymer modification in road paving applications has been growing rapidly over the last decade as it allows significant enhancements in bitumen properties with consequent improvement in road service life. In fact, the use of polymer modified bitumens (PMBs) leads to pavements characterized by higher resistance to rutting and thermal cracking and lower fatigue damage, stripping and thermal susceptibility. This paper presents a laboratory investigation concerning the effect of polymer modification on the flow behaviour of bitumens. Two different polymers, an elastomer and a plastomer, were used as bitumen modifying agents at three different percentages (2%, 4% and 6% by bitumen weight). Oscillatory mechanical analysis as well as viscosity measurements under steady state conditions were performed taking into account different testing parameters such as temperature, loading frequency and shear rate. The results confirm that the rheological properties of PMBs are strongly influenced by polymer nature and polymer content. The bitumen viscosity on the dynamic domain was combined with that in the steady-state domain, confirming the applicability of the Cox–Merz relationship for the plain bitumen and the PMBs with low polymer content. Finally, the Cross and the Carreau models were found to be suitable to fit the steady state and the dynamic results in order to determine the viscosity function of the investigated bitumens.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/189504 Collegamento a IRIS

2014
Complex Poisson’s ratio of bituminous mixtures: measurement and modeling
MATERIALS AND STRUCTURES
Autore/i: Andrea Graziani; Maurizio Bocci; Francesco Canestrari
Classificazione: 1 Contributo su Rivista
Abstract: Mechanical characterization of bituminous mixtures in the linear viscoelastic (LVE) domain is commonly limited to the measurement of a single (mono--dimensional) material function, either the Young's modulus or the shear modulus. Even under the additional hypothesis of isotropy, a complete (three-dimensional) description of the LVE response requires two material functions to be determined simultaneously and in the same experimental conditions. The measurement of viscoelastic Poisson's ratio, though generally overlooked because of the high accuracy and precision required, offers the opportunity to put aside this limitation because it can be achieved in experimental conditions that are very similar to those employed to obtain the Young's modulus. In the present experimental research the concurrent determination of the complex Poisson's ratio and the complex Young's modulus of a bituminous mixture is presented. A rheological model is employed to fit the measured complex-valued material functions and the validity of the time-temperature superposition principle is investigated. The experimental program consists of cyclic compression tests performed on cylindrical samples, with the measurement of axial and transverse strains. A conventional frequency sweep procedure is followed in a range of intermediate service temperatures. Two strain levels are chosen focusing the attention on the linear domain. In addition, samples with different air voids content are tested to observe the effect of the aggregate skeleton. Results allowed to characterize frequency and temperature dependance of the complex Poisson's ratio and make a comparison to that of the complex Young's modulus on the basis of the selected rheological model. Experimental data confirm the validity of the time--temperature superposition principle but suggest that different shift factors may be required to correctly translate the time--temperature dependance of different material functions.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/112464 Collegamento a IRIS

2014
Chemical and rheological analysis of modified bitumens blended with "artificial reclaimed bitumen"
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Stimilli A.; Ferrotti G.; Conti C.; Tosi G.; Canestrari F.
Classificazione: 1 Contributo su Rivista
Abstract: Bitumen characteristics are fundamental for the development of good performance in asphalt mixtures, particularly when the mix includes Reclaimed Asphalt (RA) as aged bitumen can strongly affect the properties of the final bituminous phase. In this study three modified bitumens with different contents (1.8%, 2.8% and 3.8%) of SBS polymer were selected. Blends of these bitumens with various percentages of an artificial reclaimed bitumen (itself polymer modified), long-term aged in laboratory, were analyzed. A chemical characterization together with classical and innovative rheological tests were performed. The chemical investigation conducted using FTIR analysis showed that different percentages of artificial reclaimed bitumen included in the blends influence the final SBS amount. Rheological tests demonstrated that the addition of the artificial reclaimed bitumen does not penalize the final bituminous blend characteristics thereby indicating that the maximum amount of Reclaimed Asphalt incorporable in a mixture (according to the highest percentage of artificial reclaimed bitumen investigated) does not appear to be limited by the rheological characteristics of the final bituminous phase.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/174502 Collegamento a IRIS

2014
Moisture sensitivity of interlayers between conventional and porous asphalt mixes
ASPHALT PAVEMENTS - Proceedings of the International Conference on Asphalt Pavements
Autore/i: Pasquini, Emiliano; Cardone, Fabrizio; Canestrari, Francesco
Editore: Y. Richard Kim
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The use of geocomposites obtained combining bituminous membranes with reinforcing geosynthetics represents a promising option for asphalt pavement application. Thanks to their waterproofing effect, such geocomposites could be successfully used also underneath porous surface layers as an alternative of bituminous tack coat. In this sense, one of the major issue related to the use of geocomposites at the interface between porous surface layers and binder courses is the prolonged contact with drained rainfall water. Given this background, a specific research study was carried out in order to evaluate the moisture sensitivity of interlayers positioned between traditional dense graded asphalt concretes and porous asphalt concretes. Particularly, two geocomposite materials produced combining an elastomeric membrane with a polyester textile and a fiberglass grid, respectively, were investigated along with a traditional reference interlayer obtained by applying hot polymer modified asphalt at the interface. In order to evaluate moisture sensitivity of such interlayers, shear tests were carried out in both dry and wet conditions on double- layered samples prepared in the laboratory. Experimental results showed that the prolonged action of the water did not produce loss of performances of studied interlayers in terms of interface shear strength.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/189506 Collegamento a IRIS

2014
Bulk and shear characterization of bituminous mixtures in the linear viscoelastic domain
MECHANICS OF TIME-DEPENDENT MATERIALS
Autore/i: Graziani A.; Bocci E.; Canestrari F.
Classificazione: 1 Contributo su Rivista
Abstract: Traffic loads and temperature variations produce three-dimensional stress–strain fields inside road pavements, and therefore the characterization of bituminous mixtures in different deformation modes is important for prediction of the performance of pavement structures. This paper presents a methodology for the bulk and shear characterization of bituminous mixtures in the linear viscoelastic domain, under the hypothesis of material isotropy, by means of uniaxial harmonic tests with the measurement of axial and transverse strains. The theoretical approach was based on the application of the elastic–viscoelastic correspondence principle and was validated by performing tension–compression tests at selected frequencies and temperatures on asphalt concrete specimens characterized by different volumetric properties. The results showed that since uniaxial tests induced both volume and shape variations, the simultaneous measurement of the complex bulk and shear moduli was possible. The validity of the time–temperature superposition principle was also verified for both deformation modes, allowing the construction of master curves for the bulk and shear moduli. The results also showed that the total dissipated energy could be decomposed into its volumetric and deviatoric fractions with excellent accuracy.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/223720 Collegamento a IRIS

2014
Synthesis of standards and procedures for specimen preparation and in-field evaluation of cold-recycled asphalt mixtures
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Gabriele Tebaldi; Eshan V. Dave; Paul Marsac; Patrick Muraya; Martin Hugener; Marco Pasetto; Andrea Graziani; Andrea Grilli; Maurizio Bocci; Alessandro Marradi; Louisette Wendling; Vincent Gaudefroy; Kim Jenkins; Andreas Loizos; Francesco Canestrari
Classificazione: 1 Contributo su Rivista
Abstract: The use of recycled asphalt (RA) materials in pavement rehabilitation processes is continuously increasing as recycling techniques, such as cold recycling (CR), are being utilised in increasing magnitude and greater awareness for use of recycled materials and consideration of sustainable practices is becoming common in the construction industry. The focus of this paper is on developing a state of the art and state of the practice summary of processes used for classification of RA as well as the curing and specimen preparation practices for cold-recycled asphalt mixtures. A variety of topics were explored through an exhaustive literature search, these include RA production methods, definition of RA materials, stockpiling practices, industrial operations, specimen curing and preparation practices and in-field evaluation of cold-recycled rehabilitation. This paper was developed through efforts of CR task group (TG6) of RILEM Technical Committee on Testing and Characterization of Sustainable Innovative Bituminous Materials and Systems (TC-237 SIB).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/150304 Collegamento a IRIS

2014
Experimental characterization of high-performance fiber-reinforced cold mix asphalt mixtures
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Ferrotti G.; Pasquini E.; Canestrari F.
Classificazione: 1 Contributo su Rivista
Abstract: Maintenance of existing road pavements assumes increasing interest as the traffic growing produces a faster deterioration of road infrastructures compromising safety and pavement serviceability. In order to guarantee long-lasting pavement repairs, maintenance activities and products must be optimized in terms of both achieved performance and curing times to reach a proper pavement serviceability. This research project focuses on the experimental characterization of a high-performance cold mix asphalt mixture reinforced with three types of fibers (cellulose, glass–cellulose, nylon–polyester–cellulose) dosed at two different contents (0.15% and 0.30% by the aggregate weight). Such materials were investigated at different curing times (1, 7, 14, 28 days) and conditions (dry and wet). Laboratory tests (Marshall, Indirect Tensile, Abrasion and Compactability) usually employed for hot mix asphalts were considered, adjusting the testing procedures taking into account the specific characteristics of cold mixes. Results showed that the mix with 0.15% cellulose fibers provides similar (for curing times of 14 and 28 days) or even higher performance (for curing times within 7 days) than the standard mixture (without fibers). Finally, the last two mixtures were compared with two cold mix asphalt mixes available on the market. The cellulosefiber- reinforced material and the standard one showed enhanced performance, allowing the conclusion that they can be more successfully used in maintenance activities.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/174503 Collegamento a IRIS

2014
Laboratory characterisation of optimised geocomposites for asphalt pavement reinforcement
GEOSYNTHETICS INTERNATIONAL
Autore/i: Pasquini E.; Bocci M.; Canestrari F.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/175107 Collegamento a IRIS

2013
Original Approach to Predict Fatigue Endurance Limit of Asphalt Binders Considering Healing Capacity
Rheology and processing of construction materials
Autore/i: F. Canestrari; A. Graziani; A. Virgili; A. Stimilli
Editore: Nicolas Roussel and Hela Bessaies-Bey
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: More phenomena interact (e.g. viscoelasticity, damage, healing) contributing to the overall behavior of binders in terms of fatigue endurance limit. However, currently there is no consolidated analytical approach inclusive of strength recovery during rest periods to characterize fatigue performance. This research proposes a criterion to determine the resistance of binders subjected to monotonous cyclic loading with multiple rest times by using a Dynamic Shear Rheometer. Main rheological properties are measured and the modeling of their evolution during each stage is proposed. The experimental program includes different binders in order to investigate the effects of SBS modification levels and aged binder contents on healing potential. Beyond the classical component related to damage analysis, the proposed criterion enables to identify other fundamental contributions, leading to a comprehensive fatigue endurance limit. This approach allows distinguishing binders taking into account their healing capacity and should provide a better correlation with in-service performance of mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/115070 Collegamento a IRIS

2013
An experimental approach to the rheological characterization of bituminous mixture based on pseudo-random stress excitations
Rheology and Processing of Construction Materials
Autore/i: A. Virgili; F. Canestrari; A. Graziani
Editore: Nicolas Roussel and Hela Bessaies-Bey
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Rheological behavior of bituminous mixtures in the small strain domain is effectively described by the Linear Visco-­‐Elasticity (LVE) theory. Since the response of LVE materials is equivalent to that of Linear Time-­‐Invariant (LTI) systems, material functions that are used to characterize LVE behavior in the frequency domain can be considered as Frequency Response Functions (FRF) of a LTI system. In this experimental research a pseudo-­‐random stress excitation, comprising a broad band of harmonic components, is used to estimate the LVE response function of a bituminous mixture using signals and systems oriented techniques. Cylindrical specimens were tested in tension-compressions configuration, both excitation (stress) and response (strain) signals were analyzed using a spectral analysis. The FRF estimated using pseudo-­random experiments is compared with conventional harmonic analysis results. Advantages and limitations of the proposed approach are highlighted, paying particular attention to the possible effects of non-­‐linearity and viscoplastic deformations.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/115071 Collegamento a IRIS

2013
Assessment of Healing in Asphalt through Diffusion Mechanism
Proceedings of EATA Conference
Autore/i: H. U. Bahia; F. Yousefirad; A. Stimilli; H. A. Tabatabaee; F. Canestrari
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/115069 Collegamento a IRIS

2013
Rheological Properties of Bituminous Binders with Synthetic Wax
INTERNATIONAL JOURNAL OF PAVEMENT RESEARCH AND TECHNOLOGY
Autore/i: Canestrari F.; Graziani A.; Pannunzio V; Bahia H.U.
Classificazione: 1 Contributo su Rivista
Abstract: Warm Mix Asphalt (WMA) has been introduced to reduce the environmental impact and improve energy efficiency of bituminous mixtures production and lay down. With this purpose, synthetic waxes are effectively used to allow reduction of temperature during mixing and compaction. Given these advantages, the basic WMA challenge is the production of a pavement mixture having, at least, the same performance as traditional HMA. This study describes the effect of a synthetic wax additive on the rheological properties of a paving grade bitumen in a wide range of temperatures. The effect of wax at mixing and compaction temperatures (T > 100°C) was evaluated using viscosity tests. A Dynamic Shear Rheometer (DSR) and a Bending Beam Rheometer (BBR) were used to investigate the rheological properties of the base and the WMA binder at midrange and low service temperatures (from 18°C to 37°C). The time-temperature superposition principle was applied to analyze the complex shear modulus and the creep stiffness modulus, through the construction of master curves. Particular attention was devoted to the study of wax effect on low temperature physical hardening.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/81957 Collegamento a IRIS

2013
Laboratory characterisation and field validation of geogrid-reinforced asphalt pavements
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Pasquini E.; Bocci M.; Ferrotti G.; Canestrari F.
Classificazione: 1 Contributo su Rivista
Abstract: In order to improve the mechanical properties of pavements, reinforcement systems can be employed in asphalt layers. However, the presence of a grid at the interface causes an interlayer de-bonding effect. Moreover, a real challenge is related to the proper in situ installation of grids. The present research aims to evaluate the effectiveness of pavement rehabilitation with fibreglass geogrids. To this purpose, a real-scale field trial was constructed and monitored through Falling Weight Deflectometer measurements. Interface shear tests and flexural tests were also carried out on double-layered samples prepared in the laboratory reproducing realscale field trial characteristics. Moreover, shear tests were also performed on in situ cored specimens. Results mainly showed that a proper installation of the reinforcement is fundamental in order to obtain suitable test results and good pavement performance.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82572 Collegamento a IRIS

2013
Improved durability of recycled porous asphalt
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: F. Frigio; E. Pasquini; G. Ferrotti; F. Canestrari
Classificazione: 1 Contributo su Rivista
Abstract: Porous asphalt mixtures are extensively used as highway surface layer due to their benefit in improving skid resistance and reducing spray and splash effects during wet conditions. Moreover, porous asphalts (PA) are also oriented towards the reduction of road traffic noise thanks to enhanced sound absorption capabilities. Nevertheless, the limited durability of porous asphalt layers leads to frequent maintenance and rehabilitation activities. In this study, the use of course reclaimed asphalt (RA), obtained by milling old porous surface layers, as aggregate in new PA mixtures was evaluated. Preliminary, Binder Bond Strength tests on coated and uncoated basalt aggregate substrates showed encouraging results in terms of adhesion properties between unaged polymer modified bitumens and substrates coated with aged bitumens, simulating RA aggregates. Thus, five porous asphalt mixtures prepared with 15% course RA aggregates and different total binder contents were studied in the laboratory. A reference PA mixture containing only virgin aggregates was also investigated for comparison purposes. Indirect tensile strength tests, particle loss (Cantabro) tests, semi circular bending (SCB) tests and repeated indirect tensile tests were carried out in both dry and wet conditions in order to evaluate acceptability, durability, fracture resistance and water sensitivity of recycled mixtures. Results showed that recycled porous asphalt mixtures can perform as well as (or even better than) reference one. In particular, recycled mixtures at equal or higher binder contents than the reference mixture demonstrated an improvement in moisture resistance and durability.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/115068 Collegamento a IRIS

2013
Mechanical Testing of Interlayer Bonding in Asphalt Pavements
State-of-the-Art-Report of the RILEM Technical Committee 206-ATB: Advances in Interlaboratory Testing and Evaluation of Bituminous Materials
Autore/i: F. Canestrari; G. Ferrotti; X. Lu; A. Millien; M.N. Partl; C. Petit; A. Phelipot-Mardelé; H. Piber; C. Raab
Editore: M.N.Partl, H.U. Bahia, F. Canestrari, C. de la Roche, H. Di Benedetto, H. Piber, D. Sybilski
Classificazione: 2 Contributo in Volume
Abstract: Steadily increasing requirements on pavement performance properties, in terms of bearing capacity and durability, as well as new innovative developments regarding pavement materials and construction, are observed worldwide. In this context interlayer bonding at the interfaces of multi-layered bituminous systems is recognized as a key issue for the evaluation of the effects, in terms of stress-strain distribution, produced by traffic loads in road pavements. For this reason a correct assessment of interlayer bonding is of primary importance, and research efforts should be addressed in order to improve the lack of correlation and/or harmonization among test methods. Following this principle RILEM TG 4 organized an interlaboratory test in order to compare the different test procedures to assess the interlayer bonding properties of asphalt pavement. The results of the experimental research are presented with a preliminary overview of basic elements, test methods and experimental investigations on interlayer bonding. Then the RILEM TG 4 experimental activities, based on the construction of three real-scale pavement sections, are presented in detail. Each pavement section wascomposed of two layers, and three different interface conditions were chosen. The first pavement was laid without interface treatment and the others with two different types of emulsion. Fourteen laboratories from 11 countries participated in this study and carried out shear or torque tests on 1,400 cores. The maximum shear or torque load and the corresponding displacement were measured, and the shear or torque strength was calculated as a function of the following parameters: diameter, test temperature, test speed, stress applied normal to the interface and age of the specimen. The results of this study are presented in terms of precision and correlations regarding the parameters which results in useful information on asphalt pavement interlayer bond tests.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82957 Collegamento a IRIS

2013
Experimental Evaluation of Shear Resistance of Improved Steel-Asphalt Interfaces
TRANSPORTATION RESEARCH RECORD
Autore/i: E. Bocci; F. Canestrari
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/115066 Collegamento a IRIS

2013
Performance Evaluation of Cold Recycled Mixture Containing High Percentage of Reclaimed Asphalt
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: A. Stimilli; G. Ferrotti; A. Graziani; F. Canestrari;
Classificazione: 1 Contributo su Rivista
Abstract: Cold recycling of asphalt pavements proved to be an effective maintenance and rehabilitation technology for both environmental and economic reasons. Nevertheless, the use of cold-recycled (CR) asphalt mixtures requires a careful assessment of their mechanical properties, especially when they are designed to replace traditional hot-mix asphalt concrete (AC) mixtures. In this study, the potential use of a CR asphalt mixture as base course of an Italian motorway was evaluated. The studied mixture was produced in a central plant employing high-reclaimed asphalt (RA) content and used to construct two experimental sections along an in-service Italian motorway. In particular, a special mixing procedure, involving the use of water vapour and bituminous emulsion, was tested. A third experimental section was constructed with the same layer thickness using the AC mixture currently used in rehabilitation projects, incorporating 30% of RA. Volumetric properties, stiffness, resistance to permanent deformation and fatigue behaviour of mixtures were investigated by performing tests on samples cored from the three test sections and on laboratory-compacted samples. Results of the mechanical tests showed that CR mixtures provide lower stiffness modulus and lower resistance to repeated loading, but better resistance to permanent deformation when compared with AC. This behaviour can be explained due to the presence of cementitious bonds that reduce thermal sensitivity and viscous response.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/115065 Collegamento a IRIS

2012
Durability Assessment of Asphalt Rubber Mixtures
INTERNATIONAL JOURNAL OF PAVEMENT RESEARCH AND TECHNOLOGY
Autore/i: Pasquini E.; Canestrari F.; Santagata F. A.
Classificazione: 1 Contributo su Rivista
Abstract: In this paper, a gap graded Asphalt Rubber Asphalt Concrete (ARAC) was studied to carefully assess durability aspects, such as moisture sensitivity, aging resistance, and abrasion resistance that contribute to establishing an important database of ARAC engineering performance. In particular, moisture sensitivity was investigated through indirect tensile and Cantabro tests on dry and wet conditioned specimens while the aging resistance was assessed in terms of change in the stiffness modulus, fatigue life, and Cantabro particle loss after the laboratory simulated long-term aging of the AR mixture. Finally, Cantabro test results on dry and un-aged samples were employed to evaluate the abrasion resistance of the studied material. Results were compared with those of reference materials tested in the laboratory or found in literature. The study provided evidence of the strong durability of the investigated Asphalt Rubber (AR) mixture.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/71049 Collegamento a IRIS

2012
An application to the European practice of the Bailey Method for HMA aggregate grading design
PROCEDIA: SOCIAL & BEHAVIORAL SCIENCES
Autore/i: Graziani A.; Ferrotti G; Pasquini E.; Canestrari F.
Classificazione: 1 Contributo su Rivista
Abstract: The Bailey Method provides a set of tools for the design and the evaluation of aggregate packing and voids of asphalt concrete grading while maintaining appropriate mixture workability and durability. In this study, concepts, procedures and parameters of the Bailey Method, that is strongly based on sieves and aggregate sizes adopted in the USA, were applied in the European perspective. To this aim, two sets of asphalt mixtures were designed applying the Bailey Method. The study shows that the European practice for aggregate grading design allows the application of the Bailey Method criteria confirming the validity of its basic principles.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/81959 Collegamento a IRIS

2012
Experimental Study on Shear Fatigue Behavior and Stiffness Performance of Warm Mix Asphalt by adding Synthetic Wax
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Petit C.; Millien A.; Canestrari F.; Pannunzio V.; Virgili A.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/71053 Collegamento a IRIS

2012
Experimental evaluation of the influence of surface coating on fiberglass geogrid performance in asphalt pavements
GEOTEXTILES AND GEOMEMBRANES
Autore/i: Ferrotti G.; Canestrari F.; Pasquini E.; Virgili A.
Classificazione: 1 Contributo su Rivista
Abstract: In road infrastructures, the maintenance of existing pavements is one of the most important issues to deal with. In order to optimize rehabilitation costs and increase pavement service life, innovative technical solutions have been developed. One of the most widespread techniques introduced for this scope, consists in the application of geogrids at the interface between different layers of pavement structures. Geogrids provide different performance depending on their characteristics, such as constituent materials, surface coating, mesh geometry and dimensions, and on their position in the pavement structure. In fact, these materials can be placed between different layers (bounded and/or unbounded) carrying out different functions. In this survey, the reinforcement of asphalt concrete layers was studied in laboratory, paying particular attention to the effects that different surface coatings, consisting in different treatments of the surface of the mesh elements of the geogrid, produce on the performance of fiberglass reinforced asphalt concrete specimens. The experimental analysis was carried out in two different stages. During the first stage, the coatings themselves were investigated, studying their adhesion properties with a conventional asphalt binder, in order to check their capability to adhere to the constitutive material of an asphalt concrete. During the second stage, a specific testing protocol was followed in order to investigate the performance of double-layered asphalt concrete specimens by means of interlayer shear tests and four-point bending tests. The results showed that the testing protocol used is suitable for studying, in laboratory, the performance of reinforced pavements, that could be influenced, both in terms of interlayer bonding between asphalt concrete layers and four-point bending test characteristics, by the application of a coating on the surface of the geogrids.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/71051 Collegamento a IRIS

2012
Analysis of structural compatibility at interface between asphalt concrete pavements and orthotropic steel deck surfaces
TRANSPORTATION RESEARCH RECORD
Autore/i: Bocci E.; Canestrari F.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/87846 Collegamento a IRIS

2012
Optimization of Geocomposites for Double-Layered Bituminous Systems
RILEM Bookseries
Autore/i: Canestrari F.; Pasquini E.; Belogi L.
Editore: Scarpas A.,Kringos N.,Al-Qadi I.L.,Loizos A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In order to improve pavement service life, reinforcement systems can be employed in asphalt layers. In this regard, geocomposites obtained by combining geomembranes with geogrids represent a promising option because they should allow both waterproofing and improved mechanical properties of asphalt pavements. However, the presence of reinforcement may cause an interlayer de-bonding effect that negatively influences overall pavement strength. Given this background, the present research aimed at evaluating the effectiveness of pavement rehabilitation with geocomposites in the laboratory. In particular, the present experimental study intended to implement new products by selecting the optimum combination among different geomembrane compounds, reinforcement types, reinforcement positions and interface conditions. The laboratory investigation was preliminarily organized to perform interface shear tests by means of the ASTRA apparatus. Then, on the basis of the results of the previous phase, the more promising configurations were selected to be further evaluated by means of the three-point bending tests. Specimens were obtained from double-layered slabs compacted in the laboratory. The results presented in this paper enabled the preliminary tuning for the selection of optimized composites to be submitted, in the near future, to performance-related dynamic tests and in situ monitoring of real scale trial sections.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82569 Collegamento a IRIS

2011
Testing and Characterization of Compacted Asphalt Pavement Materials
International RILEM Conference on Advances in Construction Materials Through Science and Engineering
Autore/i: Partl M.N.; di Benedetto H.; Canestrari F.; Bahia H.U.
Editore: RILEM Publications SARL
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: ABSTRACT. This paper summarizes some key achievements and findings by the RILEM TC 206 ATB “advanced testing and characterization of bituminous materials” taking into account new developments in the field of bituminous road materials and test methods. These developments were triggered not only by an increasing variety of materials and requirements on the performance of bituminous pavement systems but also by environmentally driven innovations in terms of recycling and low temperature asphalt and new types of binders. Work on compacted asphalt pavement materials included interlaboratory wheel tracking tests on material from real motorways well as interlayer shear bond testing on material taken from specially constructed test sections. New developments in asphalt mixture testing, such as the application of image analysis techniques, were also taken into consideration. Results show that performance of bituminous mixtures must be considered also with respect to the whole pavement system. This is particularly true, e.g., in case of rutting tests, compaction and specimen preparation evaluation as well as interlayer bond properties. It was also found that test methods developed for one type of bituminous materials do not a priory apply to another type of bituminous materials and may even lead to completely misleading conclusions as compared to real life pavement performance.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/71031 Collegamento a IRIS

2011
A strategic laboratory approach for the performance investigation of geogrids in flexible pavements
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Ferrotti G.; Canestrari F.; Virgili A.; Grilli A.
Classificazione: 1 Contributo su Rivista
Abstract: ABSTRACT: Nowadays, the increasing request in terms of road transport makes maintenance and rehabilitation of road infrastructures key tasks for road engineering. In recent years, numerous products/materials have been introduced on the market and can be used in combination or singly in order to extend pavement life and guarantee high performance. Among them, geosynthetics can play different roles in pavement structures, such as draining, reinforcement, filtering, separation, protection, and proofing. This research focuses on the validation of a strategic laboratory approach for the study of the mechanical performance of reinforced systems used in flexible pavements, combining repeated loading cycles in a four-point bending configuration with interlayer shear tests. This method can be used in further research analysis to compare unreinforced and reinforced double-layered systems. The results obtained in this investigation showed that the fiberglass grid used provides a relevant contribution to the performance of the asphalt concrete system studied.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/71045 Collegamento a IRIS

2011
Performance evaluation of gap graded Asphalt Rubber mixtures
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: PASQUINI E; CANESTRARI F; F. CARDONE; SANTAGATA F.A
Classificazione: 1 Contributo su Rivista
Abstract: In this research, an extensive laboratory test program was conducted in order to investigate the mechanical performance (stiffness, fatigue, permanent deformation and thermal cracking) of a gap graded Asphalt Rubber Asphalt Concrete (ARAC) establishing an important database of ARAC engineering performance. Additional tests were performed on Asphalt Rubber binder and ARAC mix in order to verify whether the new Mechanistic Empirical Pavement Design Guide (MEPDG) can be used effectively for AR materials. Results were compared with those of reference materials tested in laboratory or found in literature.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53959 Collegamento a IRIS

2010
Pavimentazioni Rinforzate - Progetto Pilota nella Provincia Autonoma di Bolzano
STRADE & AUTOSTRADE
Autore/i: Bocci M.; Canestrari F.; Ferrotti G.; Pasquini E.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/54829 Collegamento a IRIS

2010
Recycling Techniques and Environmental Issues relating to the Widening of an High Traffic Volume Italian Motorway
INTERNATIONAL JOURNAL OF PAVEMENT RESEARCH AND TECHNOLOGY
Autore/i: BOCCI M; F. CANESTRARI; GRILLI A; PASQUINI E; LIOI D
Classificazione: 1 Contributo su Rivista
Abstract: On the last few decades, the use of recycled materials has become important because of the limited availability of good aggregates and the difficulties and excessive disposal costs for milled materials. This study provides an environmental evaluation of a specific rehabilitation project involving several recycling techniques on one of the main Italian motorways. Three rehabilitation options are evaluated and compared in terms of their environmental impact, with particular emphasis on the construction of the subbase course. In the end, the definitive design involved different recycling techniques, including cold in-place recycling (CIPR) with bituminous emulsion and cement for the subbase layer, stabilization of the soil with lime for the embankment, the use of reclaimed asphalt in the production of hot mix asphalt, and the use of crushed cement concrete for the cement treated layers. All of these recycling methods allow the saving of the virgin aggregates, and a reduction in materials transportation and pollutant emissions coming from both the production plant and the means of transport.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/30753 Collegamento a IRIS

2010
Acoustic characterization of Asphalt Rubber mixtures in Italy
INTERNOISE 2010 - Proceedings of the 39th International Congress on Noise Control Engineering
Autore/i: PASQUINI E; F. CANESTRARI; FERROTTI G; SANTAGATA F.A; SERPILLI F
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Pavements that produce less noise at the tire/pavement interface represent an important strategic solution necessary to minimize traffic acoustic impact. Several international studies showed encouraging results in traffic noise reduction using Asphalt Rubber (AR) mixtures. The Authors present results of an Italian experience that investigates the acoustic properties of AR mixtures, paved on existing roads as wearing course, by means of in situ noise measurements carried out at different stages. These materials were studied through laboratory tests for sound absorption evaluation. Results also evaluate the properties of AR mixtures in limiting traffic noise comparing them with other typical asphalt concretes.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/42350 Collegamento a IRIS




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