Andrea GRAZIANI

Pubblicazioni

Andrea GRAZIANI

 

91 pubblicazioni classificate nel seguente modo:

Nr. doc. Classificazioni
48 1 Contributo su Rivista
34 4 Contributo in Atti di Convegno (Proceeding)
5 2 Contributo in Volume
4 5 Altro
Anno
Risorse
On the densification of cold recycled asphalt mixtures
JOURNAL OF TESTING AND EVALUATION
Autore/i: Mignini, C.; Virgili, A.; Graziani, A.
Classificazione: 1 Contributo su Rivista
Abstract: The mechanical behavior of cold recycled asphalt mixtures (CRAMs) is directly connected to their volumetric properties. Therefore, the objective of the present research was to investigate the effect of different composition factors on the densification of CRAMs. To this aim, a new empirical modeling approach for characterizing and comparing the densification of CRAMs using the gyratory compactor was proposed. The methodology was then applied to CRAMs produced using four gradations, two asphalt emulsions, two cements, various water contents, and several superplasticizer dosages. The densification curves were analyzed using three parameters representing the self-densification, the compactability, and the compaction energy. These parameters were linked using a mathematical model, which was represented using three interrelated pairwise relationships. The results showed that the grading distribution of the CRAMs was the main parameter controlling their densification behavior, whereas the water content and other composition factors played a minor role.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292744 Collegamento a IRIS

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

Experimental Study on the Grading Distribution of Cold Recycled Asphalt Mixtures Produced with Bitumen Emulsion and High Strength Cement
RILEM Bookseries
Autore/i: Mignini, C.; Cardone, F.; Graziani, A.
Editore: Springer Science and Business Media B.V.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Cold recycled asphalt mixtures (CRAM) can lead to real economic advantages only if their performance is comparable to that of traditional hot mix asphalt. This experimental study aims to investigate the effect of the grading distribution on the volumetric and mechanical properties of CRAM produced with high reclaimed asphalt dosage (>70%), bitumen emulsion and high strength cement. Four grading distributions were analysed: two continuously graded curve (derived from the Fuller-Thompson maximum density curve) with nominal maximum aggregate size (NMAS) 16 and 10 mm. The third was obtained increasing the filler dosage, and the fourth grading distribution was a gap-graded type, with NMAS 16 mm. Workability and compactability of the fresh CRAM were evaluated using the gyratory compactor. CRAM long-term complex modulus was measured using cyclic compression tests. Results showed that the gap-graded and the high-filler grading distributions allowed obtaining the lower voids in the mixture. Having fixed the number of voids in the mixture, the gap-graded CRAM showed a higher stiffness modulus and lower phase angle if compared to CRAM produced with the continuously graded curve.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292642 Collegamento a IRIS

Interphase Relations in the Characterisation of Bitumen Emulsion-Cement Composites
Proceedings of the RILEM International Symposium on Bituminous Materials. ISBM 2020
Autore/i: Miljkovic, M.; Graziani, A.; Mignini, C.
Editore: Springer Science and Business Media B.V.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Strategic research on bitumen emulsion-based materials is substantial for addressing numerous environmental effects of road infrastructure. The present specifications for bitumen emulsions are based on properties that are insufficient for a fundamental understanding of their relation to the physicomechanical behaviour of realistic coarse-graded materials for structural layers. The aim of the interlaboratory testing (ILT) of RILEM TC 280-CBE Task group 1 is to investigate the link between the intrinsic interphase relations and macroscopic physicomechanical behaviour of bitumen emulsion-cement composites. Thus, the objective of this individual research was creating the basis for the above ILT by experimental and analytical evaluation of mortar-based model systems, by investigating their physicomechanical behaviour, and by conducting the sensitivity analysis of the relations between phases. The experimental evaluation comprised compactability and volumetric evaluation of fresh mixtures, indirect tensile-based testing at different stages of curing, as well as the temporal measurement of the evaporation of water from specimens.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292647 Collegamento a IRIS

2021
Using fine aggregate matrix mortars to predict the curing behaviour of cement bitumen treated materials produced with different cements
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Mignini, C.; Cardone, F.; Graziani, A.
Classificazione: 1 Contributo su Rivista
Abstract: Cold recycling is a sustainable pavement rehabilitation technology. Among the different techniques, cement-bitumen treated materials (CBTM) take advantage of the presence of the two co-binders to achieve satisfying performance. A multiscale study addresses the effect of different cementitious binders on the mechanical behaviour of CBTM mixtures and fine aggregate matrix mortars produced with bitumen emulsion. The evolution of stiffness and strength during curing is measured and compared. Results show that the cement type has a critical effect on the mechanical behaviour and, under fixed curing conditions, changing the strength is equivalent to changing the dosage. Finally, fine aggregate matrix mortars offer an excellent prediction of mixture mechanical properties.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/286839 Collegamento a IRIS

2021
Thermo-rheological modelling of cement-bitumen treated materials in the small strain domain
TRANSPORTATION GEOTECHNICS
Autore/i: Raschia, S.; Di Benedetto, H.; Lamothe, S.; Carter, A.; Graziani, A.; Perraton, D.
Classificazione: 1 Contributo su Rivista
Abstract: Cold recycled materials (CRM) have been introduced as structural materials in road pavement structures thanks to their significant economical and environmental benefits. Among them, cement-bitumen treated materials (CBTM) are often employed because of both contributions given by bitumen (in form of emulsion) and cement. The first confers a bituminous behaviour, whereas the second ensures good short-term performance otherwise penalized by the presence of water. Water plays a fundamental role in providing workability of the mixture at the atmospheric production temperatures. Due to such peculiarities, CBTM mixtures require attention when rheological modelling is performed in the small strain domain. This paper provides an overview on the most common rheological model applied to bituminous mixtures (2S2P1D) and the main issues related to the application to CBTM mixtures are highlighted. Afterwards, another model is proposed from the literature, the DBN model, and applied to three mixtures. The mixtures were prepared to assess the effect of the bitumen emulsion used, as well as the type of curing conditions. Results showed that the DBN model seems to be an excellent tool for not only CBTM rheological modelling in the small strain domain and it is recommended for applications in wider experimental programs.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292646 Collegamento a IRIS

2021
Visco-Elasto-Plastic Characterization in the Small Strain Domain of Cement Bitumen-Treated Materials Produced at Low Temperatures
JOURNAL OF MATERIALS IN CIVIL ENGINEERING
Autore/i: Raschia, S.; Perraton, D.; Di Benedetto, H.; Lamothe, S.; Graziani, A.; Carter, A.
Classificazione: 1 Contributo su Rivista
Abstract: In the framework of recycling techniques employed in maintenance and rehabilitation projects for the road industry, cement bitumen-treated materials (CBTMs) provide good performance as well as economic and environmental benefits. Because these materials are produced with bitumen emulsion at atmospheric temperature, the environmental factors during production are extremely important to guarantee the quality of the final product. This paper focuses on the stiffness of CBTMs produced and conditioned at low temperatures, and cured in two different conditions (sealed and unsealed). The mixtures were evaluated in terms of rheological properties using complex modulus (E*) tests performed 1 year after production. Results were modeled with an adapted version of the Di Benedetto-Neifar (DBN) model for plastic dissipation for small cycles (PDSC), accordingly called DBNPDSC. Results showed that the curing conditions, as well as the low production temperatures, significantly changed the rheological properties of the material. In fact, mixing or compacting the mixtures at 5°C compared with 25°C resulted in a loss in stiffness of around 30% in the small strain domain. This model is a good tool to describe, in the small strain domain, such material behavior, which shows plastic nonviscous phenomena.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292645 Collegamento a IRIS

2021
Rheological characterisation of cold bitumen emulsion slurries
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Mignini, C.; Lo Presti, D.; Airey, G.; Graziani, A.
Classificazione: 1 Contributo su Rivista
Abstract: The performance of cold bitumen emulsion (CBE) mixtures is strongly linked to an optimised design of the binder blends and mastics. Types and dosages of bitumen, mineral additions and the workability must be characterised and optimised. This study aims at providing an approach for the fundamental characterisation of CBE materials using rotational viscometry. Firstly, a procedure for measuring the viscosity of CBE slurries using the Brookfield viscometer was investigated by comparing results obtained by using a traditional spindle geometry and a novel impeller engineered to avoid phase separation: the dual helical ribbon (DHR). Afterwards, the effect of mineral additions and bitumen emulsions types was measured and modelled, also considering the influence of their concentration. The Krieger-Dougherty model proved to be a powerful tool to fit results and provide fundamental parameters for improved CBE materials engineering characterisation. Overall, the DHR was found a promising tool for CBE slurries rheological characterisation.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292641 Collegamento a IRIS

2021
Effect of RAP Source on Compactability and Behavior of Cold-Recycled Mixtures in the Small Strain Domain
JOURNAL OF MATERIALS IN CIVIL ENGINEERING
Autore/i: Raschia, S.; Moghaddam, T. B.; Perraton, D.; Baaj, H.; Carter, A.; Graziani, A.
Classificazione: 1 Contributo su Rivista
Abstract: Cold recycled materials (CRMs) are products of modern recycling techniques that are used in maintenance and rehabilitation of pavement structures with significant economical and environmental benefits. CRM mixes are produced at ambient temperature using bitumen emulsion or foamed bitumen as a binding agent, and the aggregate phase is composed mainly of reclaimed asphalt pavement (RAP). This paper investigated the compactability of two RAP sources and their effects on the behavior of CRM mixtures tested in the small strain domain. The compactability was studied using experimental results and the compressible packing model (CPM). Complex modulus tests of CRM mixtures were conducted, and the results were modeled using the Di Benedetto-Neifar (DBN) model. Findings showed that in CRM mixtures with the same gradation and formulation, one RAP source required almost half of the compaction energy of the other source to reach the design air voids content. The rheological analysis results highlighted the impact of the RAP source on the behavior of the CRM mixes in the small strain domain.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/292644 Collegamento a IRIS

2020
Comparing the field and laboratory curing behaviour of cold recycled asphalt mixtures for binder courses
MATERIALS
Autore/i: Ferrotti, G.; Grilli, A.; Mignini, C.; Graziani, A.
Classificazione: 1 Contributo su Rivista
Abstract: The cold recycling of reclaimed asphalt (RA) for the rehabilitation of end-of-life pavements is becoming very common. Cold recycled asphalt mixtures (CRAMs) are characterised by a curing time, required to reach the material design mechanical performance. Since the laboratory simulation of the long-term field curing is not yet a standardised procedure, a CRAM was laid as binder course in a full-scale trial section that was monitored for more than two years. The comparison between field curing and oven-curing in laboratory at 40◦C was performed by carrying out indirect tensile stiffness modulus (ITSM), indirect tensile strength (ITS) and complex modulus tests, as well as measurements of the air voids content. The evolution of the ITSM as a function of the curing time (field/oven-curing) was obtained for both gyratory specimens and cores taken from the trial section at different time periods. Results showed that the material stiffness development can be accelerated with a small effect on its long-term value if oven-curing is applied a few days/weeks after compaction. A linear relationship was found between the ITS measured on the cores and their air voids content. Finally, the complex modulus tests confirmed that CRAMs provide an intermediate behaviour between asphalt concrete mixtures and cement-bound mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/286852 Collegamento a IRIS

2020
Mechanical Behaviour of Cold Recycled Asphalt Mixtures for Binder Courses Produced with Bitumen Emulsion and High Strength Cement
Lecture Notes in Civil Engineering
Autore/i: Mignini, C.; Cardone, F.; Graziani, A.
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Cold recycled asphalt mixtures (CRAM) are sustainable solutions for maintenance and rehabilitation of road pavements. Notwithstanding the environmental benefits, CRAM may exhibit lower performances compared to traditional hot mix asphalt. Besides, CRAM require a curing period to reach their long-term properties, and thus, they are usually employed in base courses. This work investigates the mechanical behaviour of CRAM with bitumen emulsion and high strength cement to verify if they are suitable for binder courses. Six CRAM were produced using 80% of reclaimed asphalt, modified emulsion and two high strength cement: sulfo-aluminous and Portland-slag cement. For comparison, two additional mixtures were produced using traditional emulsion. The CRAM had an emulsion content of 4.2% or 5.0%, and residual bitumen to cement ratio of 1.0 or 1.2. After curing periods from 6 h to 1 year, the indirect tensile stiffness modulus (ITSM) and indirect tensile strength (ITS) were assessed. Their thermal sensitivity was evaluated as well, measuring ITSM at different temperatures. Results indicate that high strength cement leads to satisfactory mechanical behaviour in the long-term. Compared to Portland-slag cement, sulfo-aluminous cement increases the rate of development of ITS and ITSM in the early stage of about 50% and 25%, respectively.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/286842 Collegamento a IRIS

2020
Repeatability Study on the Laboratory Production Process of Cement Bitumen Treated Materials with Foamed Bitumen
Lecture Notes in Civil Engineering
Autore/i: Raschia, S.; Rahmanbeiki, A.; Perraton, D.; Carter, A.; Graziani, A.; Grilli, A.
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Cold recycled materials are mixes with high percentages of reclaimed asphalt (RA), while the binding phase is commonly composed of Portland cement and bitumen (emulsion or foam). The reproduction of such materials in the laboratory is an important issue for an accurate mix design, even more when applying a volumetric approach. Particularly, the lack of a specific control on the reliability of the foaming bitumen machine seems to hinder the potentiality of these mixtures. Hence, the goal of this study is to assess the composition variability of several batches produced in the laboratory starting from a specific cement-bitumen treated materials (CBTM) recipe and production procedure. An ignition oven was used to measure RA binder and the effective foamed bitumen amounts in produced specimens and a comparison between maximum dry density and theoretical maximum dry density was carried out. The results have shown that the volumetric approach is a suitable tool to obtain the desired volumetric properties in CBTM produced with foamed bitumen. A certain variability between the theoretical maximum dry density and the measured value can be caused by the variability of bitumen content in the mixture.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/286843 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
Use of fine aggregate matrix to analyze the rheological behavior of cold recycled materials
MATERIALS AND STRUCTURES
Autore/i: Graziani, A.; Raschia, S.; Mignini, C.; Carter, A.; Perraton, D.
Classificazione: 1 Contributo su Rivista
Abstract: Nowadays, one of the main challenges to a wider application of cold recycling techniques is the lack of reliable information on the mechanical behavior of cold recycled materials (CRM). In this context, measurement and modelling of the complex modulus of CRM mixtures may give an important contribution to the design and analysis of pavements including cold recycled layers. In this study, we analyzed the rheological behavior of CRM mixtures produced using bitumen emulsion and cement through the study of their fine aggregate matrix (FAM). Starting from a fixed CRM mixture composition, we compared different FAM mortars, focusing on the effect of water and air content. Then, we selected a composition as representative of the FAM in the mixture and investigated the evolution of both materials during a fixed curing period. Next, we measured the complex modulus of the CRM mixture and FAM at two curing stages and applied a rheological model to simulate and compare their behavior. Results showed that the properties of CRM mixtures are comparable to those of FAM mortars produced using all the binding agents (bitumen emulsion and cement) and a fraction of the voids contained in the mixture. Despite the huge difference in volumetric compositions, the FAM mortar controlled the curing and the thermo-rheological behavior of the CRM mixture, while the coarse reclaimed asphalt aggregate fraction and the voids mainly affected the asymptotic properties (equilibrium and glassy moduli) and the non-viscous dissipation component.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/286841 Collegamento a IRIS

2020
Cold in-place recycling for a base layer of an Italian high-traffic highway
Lecture Notes in Civil Engineering
Autore/i: BOCCI, EDOARDO; GRAZIANI, Andrea; Bocci, M.
Editore: Springer
Classificazione: 2 Contributo in Volume
Abstract: Cold in-place recycling (CIR) has increasing interest worldwide due to the large economic and environmental benefits deriving from reduction of atmospheric emissions, preservation of natural resources, no hauling of the material to the recycling plant and back to the jobsite. However, a unique protocol for the structural rehabilitation of highly trafficked highways based on CIR has not been still developed, discouraging their application in the upper layers of the pavement (base layer). This paper describes a case study where a cold recycled asphalt base (CRAB), containing 100% of reclaimed asphalt treated with polymer-modified bitumen emulsion and cement, has been applied in the reconstruction of the SS268 divided highway in southern Italy. The technical approach followed in this project included the preliminary execution of falling weight deflectometer tests to estimate the subgrade stiffness, the design of the pavement structure through a mechanistic-empirical procedure, the mix design of the CRAB and the validation of the construction procedure and mix properties in a trial section. This paper aims to provide a protocol for the design and construction of CIR mixtures, allowing their use as base layer for the highways interested by a high traffic.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/271155 Collegamento a IRIS

2020
A new approach to determine absorption water of reclaimed asphalt pavement aggregate (RAP) for the production of cold recycled mixtures (CRM)
Proceedings of the 5th International Symposium on Asphalt Pavements & Environment (APE)
Autore/i: Raschia, S.; Panwar, S.; Chauhan, T.; Carter, A.; Graziani, A.; Perraton, D.
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Absorption ability of aggregates is one of the most important material characteristics in the perspective of a bituminous mixture mix design. In particular, this aspect gains more importance in the framework of cold recycled mixtures (CRM). Since such materials are produced at ambient temperature, the workability is ensured by the employment of bitumen emulsion and water. As a consequence, the water absorption of the aggregate phase needs to be clearly stated, in order to know the amount of effective water which will affect workability and mechanical properties of the mixtures. The determination of absorption water is clearly described in international standards (ASTM and European Standard). Nevertheless, both practices leave some aspects unclear, leading to misleading results if applied to the same material. In this paper, a new approach to determine the water absorption of reclaimed asphalt pavement (RAP) used to produce CRM is proposed. Results showed that both standards used in this work gave different absorption water values, making difficult to assess which one is reliable. The new approach highlighted the possibility to evaluate in a more precise and scientific way the absorption water of RAP aggregate, studying the volumetric changes at different water content under compaction.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/271163 Collegamento a IRIS

2020
Influence of low production temperatures on compactability and mechanical properties of cold recycled mixtures
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Raschia, S.; Perraton, D.; Graziani, A.; Carter, A.
Classificazione: 1 Contributo su Rivista
Abstract: In cold regions, the production of Cement-Bitumen Treated Materials (CBTM) represents an issue in terms of annual time available for production. The objective of this research is to study the influence of different combinations of production temperatures for mixing, compacting and curing (developed in two steps) on the mechanical properties of CBTM produced with two sources of bitumen emulsion. Workability, compactability, indirect strength and other additional tests were involved in the analysis. Findings highlighted the critical effect of transportation and compaction temperatures on CBTM workability. Moreover, the emulsion source significantly affects the mixture strength when produced at low temperatures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/271161 Collegamento a IRIS

2020
Effect of water and cement content on the mechanical properties of cold recycled mixtures (CRM) with bitumen emulsion
Proceedings of the 5th International Symposium on Asphalt Pavements & Environment (APE)
Autore/i: Raschia, S.; Chauhan, T.; Panwar, S.; Carter, A.; Graziani, A.; Perraton, D.
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Cold recycled mixtures (CRM) treated with bitumen emulsion are innovative materials in road pavement construction industry which gained visibility in the last decades. They are produced at ambient temperatures thanks to the employment of bitumen emulsion, water and additional hydraulic binders. In this research, four CRM mixes are studied analysing the effect of two water contents and two cement dosages. The mechanical properties of the mixes were studied in terms of Indirect Tensile Ratio (ITR), Indirect Tensile Stiffness Modulus (ITSM) test and dynamic modulus test, after a curing period of 14 days. Moreover, results analysis is improved by images obtained at the scanning electron microscope (SEM). From the results, the presence of more water decreased the indirect tensile strength (ITS) in both dry and wet conditions, even if the water susceptibility was generally low (ITR > 80%). The PUNDIT measurements along curing highlighted the progressive increase of the dynamic modulus, which after curing was higher in the mixtures with cement. At the end, SEM images highlighted the effect of the water content in the dispersion of the bituminous phase, as well as the presence of cement hydration products.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/271209 Collegamento a IRIS

2019
EVALUATING THE CRACKING RESISTANCE OF CEMENT-BITUMEN TREATED MATERIALS USING THE SEMI-CIRCULAR BENDING TEST
New generation of construction materials
Autore/i: Mignini, Chiara; Cardone, Fabrizio; Morbi, Alessandro; Setti, Luca; Graziani, Andrea
Editore: RILEM sarl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Cement-bitumen treated materials (CBTM) are produced using cold recycling technologies for the rehabilitation of bituminous pavements. Bitumen emulsion and cement are used as binders, and thus jointly contribute to the mechanical performance of the mixtures. This paper focuses on the cracking resistance of CBTM, which is related to the presence and relative effect of bituminous and cementitious bonds within the mixtures. The objective is to evaluate the influence of different cement types, bitumen-to-cement ratios (1.3 and 0.8) and curing conditions (free and restricted evaporation). The semi-circular bending (SCB) test was used to evaluate the cracking resistance of mortar specimens whose composition was derived from the mixtures’ composition removing the coarse aggregates. The SCB specimens cut from gyratory compacted specimens were tested at 10 °C after 28 days of curing at 25 °C. The results analysis indicates that in the crack initiation phase, the behaviour of CBTM mortars depends on the combined presence of cementitious and bituminous bonds, whereas, in the crack propagation phase, the effects of cement type and dosage prevail and may lead to a brittle behaviour.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267169 Collegamento a IRIS

2019
FIELD BEHAVIOUR OF COLD-RECYCLED ASPHALT MIXTURES FOR BINDER COURSES
New generation of construction materials
Autore/i: Grilli, Andrea; Mignini, Chiara; Graziani, Andrea
Editore: RILEM sarl
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: A new awareness on sustainable materials and construction techniques is promoting field applications of cold bitumen emulsion mixtures. Cold in-plant recycling (CPR) techniques with bitumen emulsion ensure important benefits in terms of energy saving and amount of recycled materials while maximising the performance and production stability of mixtures. This study describes the construction of a pavement trial section where a cold-recycled asphalt mixture (CRAM) was placed as binder course. The CRAM was manufactured in-plant, using about 90% of reclaimed asphalt, bitumen emulsion and cement. The evolution of indirect tensile stiffness modulus (ITSM) was monitored on both laboratory-compacted specimens and cores extracted from the pavement. From the analysis of results, it can be affirmed that the increase of ITSM due to the curing process was faster for laboratory specimens with respect to field
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267168 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
Complex Modulus Testing and Rheological Modeling of Cold-Recycled Mixtures
JOURNAL OF TESTING AND EVALUATION
Autore/i: Graziani, Andrea; Mignini, Chiara; Bocci, Edoardo; Bocci, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: This research compares the rheological behavior of different cold-recycled mixtures (CRMs) produced in-place through full-depth reclamation. Reclaimed asphalt pavement (RAP) obtained from the milling of the old asphalt layers was blended with reclaimed unbound aggregate from the existing subgrade. Asphalt emulsion, foamed asphalt, and portland cement were employed as stabilizing agents. The complex modulus was measured on cylindrical cores, applying a sinusoidal strain with an amplitude of 30 microstrain at testing temperatures ranging from 0°C to 50°C and frequencies ranging from 0.1 to 20 Hz. The Huet-Sayegh (HS) rheological model was applied to simulate the experimental data. The results showed that the behavior of CRM is thermo- and frequency-dependent and that the time-temperature superposition principle can be applied. The HS model provides an excellent fitting of the dynamic modulus data, whereas fitting of the loss angle data was improved, introducing a temperature- and frequency-independent correction. The RAP influences the rheological behavior, but viscous dissipation is mainly due to the asphalt-stabilizing agents (emulsion residue or foamed asphalt).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/268080 Collegamento a IRIS

2019
Laboratory mechanical characterisation of cold recycled mixtures produced with different RAP sources
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Raschia, S.; Graziani, A.; Carter, A.; Perraton, D.
Classificazione: 1 Contributo su Rivista
Abstract: Cold Recycled Mixtures (CRM) are composed of high amounts of Reclaimed Asphalt Pavement (RAP) together with bitumen emulsion. As additional binder, some ordinary cement is normally employed. Since RAP aggregates represents almost the entire solid structure, it is important to fully characterise Cement-Bitumen Treated Materials (CBTM) produced with different RAP materials. This work focuses the characterisation at small strain level, investigating the stiffness modulus at three testing temperatures; at the failure point, measuring the Indirect Tensile Strength; and studying the fracture behaviour, in Semi-Circular Bending Test configuration. From the results, it is possible to confirm the influence of different RAP materials, also characterised by different aggregates Nominal Maximum Size. As a consequence, a reliable RAP classification can allow a better prediction of the final CBTM mechanical properties.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/267166 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
Effect of curing on the indirect tensile failure energy of cement-bitumen treated materials
7th International Conference "Bituminous Mixtures and Pavements"
Autore/i: Mignini, Chiara; Cardone, Fabrizio; Graziani, Andrea; Morbi, Alessandro; Setti, Luca
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Cold recycling technologies allow the use of high percentage of reclaimed asphalt (RA) through mixing at ambient temperature and thus, they represent a sustainable solution for road construction and rehabilitation. Specifically, cement-bitumen treated materials (CBTM) are produced using both bituminous and cementitious binders. Consequently, they require a curing time to reach adequate mechanical properties. This study focuses on CBTM manufactured using bitumen emulsion (2.0% of residual bitumen), cement (1.5% and 2.5%) and 80% of RA. Indirect tensile strength (ITS) was evaluated at times ranging from 1 to 90 days after sealed and unsealed curing. The transverse deformation of the specimens was measured to calculate the failure energy. Results show that ITS and failure energy increase with curing time and are higher in unsealed conditions. The horizontal strain in the early stage depends on the binders’ dosage and curing conditions whereas, in the long term it is similar for all the mixtures investigated.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263584 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
Effect of gradation on volumetric and mechanical properties of cold recycled mixtures (CRM)
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Raschia, S.; Mignini, C.; Graziani, A.; Carter, A.; Perraton, D.; Vaillancourt, M.
Classificazione: 1 Contributo su Rivista
Abstract: In recent times, recycling using cold bituminous mixtures has become one of the most interesting techniques in pavement engineering from sustainability aspect. This study focuses on the clarification of the steps concerned with the cold mixture mix design to determine the initial aggregate gradation of the mixture. The study has been developed involving procedures followed in Canada and Italy. In both the cases, three different gradations, normally employed in the production of traditional bituminous mixtures, were compared. The effect conferred by the gradation type has been studied in terms of workability, compactability and mechanical properties. Results show that in both the procedures the gradation influenced the workability and the compaction behaviour of the mixtures studied. At the same time, in terms of mechanical properties, the gradation influenced the strength of the final mixture in only one of the procedures applied.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/271214 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

2019
Slurry surfacing: a review of definitions, descriptions and current practices
RILEM TECHNICAL LETTERS
Autore/i: Grilli, Andrea; Graziani, Andrea; Carter, Alan; Sangiorgi, Cesare; Pivoto Specht, Luciano; Copetti Callai, Sergio
Classificazione: 1 Contributo su Rivista
Abstract: Cold bitumen emulsions (CBE) are currently used worldwide for both non-structural (cold surface treatments) and structural (cold bituminous mixtures) paving applications. Among non-structural applications, bituminous slurry surfacings (BSS) allow to improve surface properties and extend the pavement’s life. However, selection of constituents, mix design, application and quality control procedures for BSS are mostly based on local experience and empirical tests. Thus, the use of BSS is associated to higher technical risks with respect to the use of traditional hot-mix technologies. In this context the RILEM Technical Committee 280-CBE TG2 “Multiphase characterisation of cold bitumen emulsion materials” aims to collect worldwide theoretical knowledge and experiences on BSS and to inspire new standards, specifications and guidelines encompassing the wide set of existing practices. This paper summarizes the first part of the literature review carried out as part of the TC workplan and focuses on the definition, the description and the application method for BSS. National standards, construction specifications and best practice documents from North America, South America, Europe and Australia are analysed and compared.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/276123 Collegamento a IRIS

2018
Complex Modulus of Cold Recycled Mixtures: measurement and modelling
2018 ISAP Conference
Autore/i: Graziani, Andrea; Mignini, Chiara; Bocci, Edoardo; Bocci, Maurizio
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: In the present study, the complex modulus E* of three types of cold recycled mixtures was measured in the laboratory using cyclic compression tests. The mixtures, that were produced in situ using the full-depth reclamation technique, were characterised by the same 100% reclaimed aggregate composition, whereas bitumen emulsion, foamed bitumen and portland cement were employed as binding agents. Complex modulus testing was carried out on cylindrical specimens cored from the pavement seven years after construction. A sinusoidal strain with amplitude of 30 microstrain was applied at testing temperatures ranging from 0 to 50 °C and frequencies ranging from 0.1 to 20 Hz. Results showed that the time-temperature superposition principle was fully verified for the stiffness modulus whereas some discrepancy was highlighted by the loss angle. The Huet-Sayegh rheological model was applied to simulate the experimental data. Model fitting based only on the stiffness modulus provided excellent results. Indeed, the fitted rheological model was also able to simulate the loss angle variation quite well, but with some underestimation (about 3°) of the measured values. It can be concluded that other dissipation mechanism, in addition to the “classical” viscous type, were influent for behaviour of the studied cold recycled mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259785 Collegamento a IRIS

2018
A Laboratory Approach for Characterizing the Evolutive Behavior of Cold Recycled Mixtures
Transportation Research Board 97th Annual Meeting
Autore/i: Graziani, Andrea; Iafelice, Christian; Raschia, Simone; Carter, Alan; Perraton, Daniel
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Cold recycled mixtures (CRM) offer a cost-effective and sustainable alternative to conventional hot technologies for the rehabilitation of asphalt pavements. Reclaimed asphalt pavement (RAP) is the main aggregate source for CRM, while binders normally include asphalt emulsion (or foamed asphalt) and portland cement. Because of the presence of water, emulsion and portland cement, CRM are evolutive materials and thus require a certain curing time to develop their long-term properties. The present study describes a laboratory approach for characterizing the properties of CRM, focusing on their evolutive behavior. The experimental activities were carried out in parallel at École de Technologie Supérieure in Montreal, Canada and at Università Politecnica delle Marche in Ancona, Italy. A common reference CRM composition was chosen in terms of grading curve, asphalt emulsion and portland cement contents. Locally available materials were selected to produce the CRM. Water loss by evaporation and indirect tensile strength (ITS) were measured for a 28-days period, in fixed curing conditions. The evolution of these properties was analyzed using the Michalis-Menten model, in order to achieve a quantitative characterization of the curing process. The results showed that different dosages of water resulted in different rates of water loss by evaporation, but did not penalize the development of ITS. Moreover, for both CRM, a good correlation was found between water loss and ITS. Finally, the data showed that after 28 days of curing in the selected laboratory conditions, the evaporation process was virtually completed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259783 Collegamento a IRIS

2018
Recycled Glass Filler in Cold Recycled Materials Treated with Bituminous Emulsion
Transportation Research Board 97th Annual Meeting
Autore/i: Raschia, Simone; Badeli, Saeed; Carter, Alan; Graziani, Andrea; Perraton, Daniel
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259784 Collegamento a IRIS

2018
Testing the bond strength between cold bitumen emulsion composites and aggregate substrate
MATERIALS AND STRUCTURES
Autore/i: GRAZIANI, Andrea; VIRGILI, Amedeo; CARDONE, Fabrizio
Classificazione: 1 Contributo su Rivista
Abstract: Bitumen emulsion mixtures derive their mechanical properties from the cohesion provided by the bituminous mastic formed by bitumen and filler, and from its adhesion to the aggregate particles. In cold bitumen emulsion mixtures, the mastic film is produced upon emulsion breaking and the bond strength between mastic and aggregate must be evaluated considering the evolutive nature of the material, and thus the curing process. In this study, the binder bond strength (BBS) test was used to evaluate the bond strength between a bitumen emulsion, a cold mastic prepared using limestone filler and two aggregate substrates (limestone and basalt). A 2k factorial experiment was conducted also considering the influence of substrate moisture (dry and wet), curing time (24 and 72 h), curing temperature (25 and 40 °C) and moisture damage on the bond strength. The results demonstrated that, although both emulsion and mastic showed good affinity with the aggregate substrates, the adhesion bond between emulsion and basalt substrate was the most durable and that the use of a limestone filler penalised the moisture sensitivity of the systems. The BBS test was also able to show the positive effect of curing time and temperature on the bond strength.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/252906 Collegamento a IRIS

2018
Evaluation of bonding between reclaimed asphalt aggregate and bitumen emulsion composites
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Cardone, F.; Virgili, A.; Graziani, A.
Classificazione: 1 Contributo su Rivista
Abstract: The bond strength between bituminous binder and aggregate is fundamental to evaluate the performance and durability of cold bitumen emulsion mixtures (CBEM). The interaction developed at binder-aggregate interface is strongly dependent on the properties of aggregate, residual bitumen and emulsifiers, as well as on the environmental conditions affecting emulsion breaking. When reclaimed asphalt (RA) aggregate is used in the production of CBEM, the adhesion issue becomes more complex because the residual bitumen interacts with the aged bitumen film coating the RA aggregate surface. In this research, the binder bond strength (BBS) test was performed to evaluate the bonding between a bitumen emulsion, a cold mastic prepared using limestone filler and artificial RA substrates produced using two aggregate sources. The moisture sensitivity along with the effect of curing temperature and time on the bond strength development were also evaluated. The results showed good affinity between both cold bitumen emulsion composites and the aged bitumen film coating the RA substrate, also highlighting a reduced moisture sensitivity for most of the tested systems. Moreover, the BBS results allowed to properly discriminate the effect of curing temperature and time on bond strength between the artificial RA aggregate and the cold bitumen emulsion composites.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259249 Collegamento a IRIS

2018
Experimental study of bitumen emulsion–cement mortars: mechanical behaviour and relation to mixtures
MATERIALS AND STRUCTURES
Autore/i: Mignini, Chiara; Cardone, Fabrizio; Graziani, Andrea
Classificazione: 1 Contributo su Rivista
Abstract: Cold bitumen emulsion mixtures are ecofriendly materials for road pavement construction. Portland cement and other supplementary cementitious materials are added to the mixtures to improve their performance. In bitumen emulsion–cement (BEC) mixtures, the two binders affect the mechanical behaviour and the curing process. In this research, BEC mixtures are considered as multiphase composite materials consisting of a mortar matrix and coarse aggregate inclusions. The main objectives are to identify the composition of BEC mortar phase and to compare mixtures and mortars throughout the curing process. Starting from two BEC mixtures containing 80% reclaimed asphalt, eighteen mortars were manufactured by changing their water and air voids content. Then, two design composition were selected to analyse the curing process by monitoring indirect tensile strength (ITS), indirect tensile stiffness modulus (ITSM) and moisture loss. Results showed that the short-term ITS of mortars (1 day of curing) increased by reducing their water and their air voids content. During curing (from 1 to 28 days), the mechanical properties (ITS and ITSM) of mixtures and mortars increased in a similar way. Unique relationships were identified between mortar and mixture properties, regardless of bitumen to cement (B/C) ratio, curing time and curing condition. In terms of predictive behaviour, the design composition slightly underestimated mixture stiffness and overestimated mixture strength.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/263585 Collegamento a IRIS

2018
The evolution of the mechanical behaviour of cold recycled mixtures stabilised with cement and bitumen: field and laboratory study
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: GODENZONI, CARLOTTA; GRAZIANI, Andrea; BOCCI, EDOARDO; BOCCI, MAURIZIO
Classificazione: 1 Contributo su Rivista
Abstract: Road construction and maintenance involve huge amounts of materials that can include wastes from the demolition of old asphalt pavements. Recycling allows environmental and economic benefits to be achieved, by reducing the consumption of natural resources. These advantages are maximised with cold-recycling, in particular when full depth reclamation (FDR) is adopted as road rehabilitation technique. The aim of this research was to compare different FDR tech- niques, which produce cement-treated material and cement–bitumen treated material (CBTM) combining the use of cement and bitumen emulsion or foamed bitumen. The FDR was applied in a trial section built along an in-service highway and monitored with annual falling weight deflectometer (FWD) surveys in order to evaluate the performance evolution. Results high- lighted that, because of the effect of temperature, the FWD deflections were not suitable to accurately evaluate the evolution of the mechanical behaviour of the cold recycled mixture (CRM) layers. However, the temperature-corrected FWD moduli allowed to conclude that the performance of the CRM layers was similar.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/245814 Collegamento a IRIS

2018
A procedure for characterizing the curing process of cold recycled bitumen emulsion mixtures
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Graziani, Andrea; IAFELICE, CHRISTIAN; Raschia, Simone; Perraton, Daniel; Carter, Alan
Classificazione: 1 Contributo su Rivista
Abstract: Due to the presence of water, emulsion and cement, cold recycled mixtures (CRM) are evolutive materials and thus require a certain curing time to develop their long-term properties. The present study describes a laboratory approach for characterizing the properties of CRM, focusing on their evolutive behaviour. The experimental activities were carried out in parallel at the École de technologie supérieure (ÉTS) in Montréal, Canada and at the Università Politecnica delle Marche in Ancona (UNIVPM), Italy. The evolution of water loss by evaporation and indirect tensile strength (ITS) was measured and analyzed using the Michalis-Menten model, in order to achieve a quantitative characterization of the curing process. The results showed that different dosages of water resulted in different rates of water loss by evaporation, but did not penalize the development of ITS. Moreover, for both CRM, a good correlation was found between water loss and ITS. Finally, the data showed that after 28 days of curing in the selected laboratory conditions, the evaporation process was virtually completed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259781 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
Three-dimensional characterisation of linear viscoelastic properties of bituminous mixtures
RILEM State-of-the-Art Reports
Autore/i: Graziani, A.; Di Benedetto, H.; Perraton, D.; Sauzéat, C.; Hofko, B.; Nguyen, Q. T.; Pouget, S.; Poulikakos, L. D.; Tapsoba, N.; Grenfell, J.; Cannone Falchetto, A.; Wistuba, M.; Petit, C.
Editore: Springer Netherlands
Classificazione: 2 Contributo in Volume
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/254082 Collegamento a IRIS

2017
Instrumented test section for analyzing the curing process of cold-recycled mixtures
Bearing Capacity of Roads, Railways and Airfields
Autore/i: Godenzoni, C.; Graziani, A.; Bocci, M.; Grilli, A.; Bocci, E.
Editore: CRC Press
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: An instrumented pavement section was realized during the widening of an Italian motor- way in order to evaluate the curing process and performance of two types of cold-recycled mixtures: a cement treated material (3% of cement) and a cement-bitumen treated material (2% of cement and 3% of bitumen emulsion). The mixtures were fabricated in place by full-depth reclamation and, before the construction of the upper courses, the recycled layer was instrumented with pressure cells, asphalt strain gauges, time domain reflectometer probes and ther mistors. After construction, part of the recycled layer was sealed with bitumen emulsion in order to evaluate the effect of free or prevented water evaporation on the curing process. This paper describes the site preparation, the pavement construction phases, sen- sor installation and the setup of the data acquisition system. The moisture data recorded by the time domain reflectometer probes during 90 days are presented. Results show that moisture loss was higher for the cement treated material that was characterized by higher cement content. In addition, covering the layer with a bitumen emulsion membrane (i.e. preventing water evaporation) induced a marked reduction (around 50%) of the initial curing rate
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/259786 Collegamento a IRIS

2017
Recommendation of RILEM TC 237-SIB on complex Poisson’s ratio characterization of bituminous mixtures
MATERIALS AND STRUCTURES
Autore/i: GRAZIANI, Andrea; Di Benedetto, H.; Perraton, D.; Sauzéat, C.; Hofko, B.; Poulikakos, L. D.; Pouget, S.
Classificazione: 1 Contributo su Rivista
Abstract: This recommendation describes how to characterize the isotropic three-dimensional linear viscoelastic behaviour of bituminous mixtures through the simultaneous measurement of the complex Young’s modulus (E ) and the complex Poisson’s ratio (m ). The guidelines given herein are based on the results of a RILEM round robin test organized by the RILEM Technical Committee 237-SIB ‘‘Testing and characterization of sustainable innovative bituminous materials and systems’’ and focus on the testing procedure, measurement setup, data analysis and presentation of results. Indications for the preparation of a tests report are also given.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/245815 Collegamento a IRIS

2017
Complex modulus characterisation of cold-recycled mixtures with foamed bitumen and different contents of reclaimed asphalt
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Godenzoni, Carlotta; Graziani, Andrea; Perraton, Daniel
Classificazione: 1 Contributo su Rivista
Abstract: Cold-in place recycling with foamed bitumen (FB) is currently employed for the rehabilitation of road pavements, from local roads to heavy-duty motorways. The mechanical properties of FB mixtures may vary from that of an improved granular material to that of an asphalt con- crete, depending on their composition. The objective of the present study was to characterise the linear viscoelastic (LVE) response of FB mixtures with different contents of reclaimed asphalt (50%, 70% and 0%). This objective was tackled by measuring the complex Young’s modulus by means of uniaxial cyclic compression tests, in a range of temperatures (from − 20°C to 55°C) and frequencies (from 0.03 to 10 Hz). The thermo-rheological behaviour was modelled using the Huet–Sayegh model, commonly used for bituminous mixtures. In order to focus on the influence of reclaimed asphalt content, the same grading and FB content were used for all the mixtures. In addition, an effort was made to produce mixtures with similar vol- umetric properties. Considering all the tested mixtures, the stiffness modulus ranged between 171 and 4075 MPa, whereas the phase angle ranged between 4° and 18°. Though these values are well below those normally measured on asphalt mixtures, the frequency and temperature variations clearly highlight a typical asphalt-like behaviour. In addition, the time–temperature superposition principle can be considered valid, regardless of the reclaimed asphalt content. Overall the experimental results showed that it is possible to characterise the LVE response of cold-recycled FB mixtures using the same experimental and analytical approach adopted for asphalt mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/231150 Collegamento a IRIS

2017
Rheological characterization of cold bituminous mastics produced with different mineral additions
Transport Infrastructure and Systems
Autore/i: Godenzoni, C; Bocci, M; Graziani, A
Editore: CRC Press/Balkema
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/246601 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
An application of the Michaelis–Menten model to analyze the curing process of cold recycled bituminous mixtures
INTERNATIONAL JOURNAL OF PAVEMENT RESEARCH AND TECHNOLOGY
Autore/i: GRAZIANI, Andrea; Godenzoni, Carlotta; CARDONE, Fabrizio; Bocci, Edoardo; BOCCI, MAURIZIO
Classificazione: 1 Contributo su Rivista
Abstract: In this paper the laboratory curing process of two types of cold recycled mixtures manufactured during the construction of an experimental pavement section along an Italian motorway was investigated. Specifically, a cement–bitumen treated material (CBTM) mixture and a cement treated material CTM) mixture, produced both on site and in laboratory, were tested. Moisture loss by evaporation (DW), indirect tensile stiffness modulus (ITSM) and indirect tensile strength (ITS) were measured in order to evaluate the curing process. The measured data were analyzed using the nonlinear Michaelis–Menten (MM) model with the aim to characterize the rate at which the mixture properties evolve over time and their values at the long-term cured state. The results showed that the adopted curing variables (DW, ITSM and ITS) gave a comparable description of the curing process, when evaporation was llowed and that the MM model gave an appropriate description of the evolutive behavior of CBTMs and CTMs. Finally, the results showed that in the initial curing stage the effect of cement hydration prevailed on that of emulsion breaking.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/246524 Collegamento a IRIS

2016
Effect of curing on the physical and mechanical properties of cold-recycled bituminous mixtures
MATERIALS & DESIGN
Autore/i: Graziani, Andrea; Godenzoni, Carlotta; Cardone, Fabrizio; Bocci, Maurizio
Classificazione: 1 Contributo su Rivista
Abstract: Cold recycling of bituminous pavements is an effective way to reduce cost of pavement maintenance. Depending on composition, cold-recycled mixtures with a wide range of mechanical properties can be produced. However, regardless of composition, a distinctive feature of cold-recycled mixtures is the requirement for a curing period to develop the long-term mechanical properties. The main objective of this study was to characterize the curing process of cold-recycled mixtures by analysing the rate at which mixture properties evolve over time and their value in the long-term cured state. The study was focused on two mixtures with a fixed dosage of bituminous emulsion (3.3%) and two cement dosages (1% and 2.5%). Moisture loss by evaporation, ITS and ITSM were measured over time (100 days), considering two curing temperatures (25 °C and 40 °C). The evolution of such properties was modelled using two asymptotic regression models. Results showed that the Michaelis–Menten model effectively describes the evolution of material properties over time, the relation between water loss and mechanical properties and the relation between ITSM and ITS. Cement dosage had an important impact on the long-term values of material properties, whereas curing temperature mainly influenced the rate of curing.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/231142 Collegamento a IRIS

2016
3Dim experimental investigation of linear viscoelastic properties of bituminous mixtures
MATERIALS AND STRUCTURES
Autore/i: Perraton, Daniel; Di Benedetto, Hervé; Sauzéat, Cédric; Hofko, Bernhard; GRAZIANI, Andrea; Nguyen, Quang Tuan; Pouget, Simon; Poulikakos, Lily D.; Tapsoba, Nouffou; Grenfell, James
Classificazione: 1 Contributo su Rivista
Abstract: As part of RILEM TC 237-SIB, TG3 performed a Round Robin Test to evaluate the capacity to measure Poisson’s ratio of an asphalt mixture in the laboratory and to check whether it could be considered as an isotropic property. Five laboratories located in five different countries took part in the testing program. This paper presents the different techniques used by the laboratories, reports the measured Poisson’s ratios and comments upon the differences found between the results. Sinusoidal or haversine loading either in tension–compression or pure compression was applied to the specimens over a range of frequencies and temperatures. During the loading both the axial and radial strains were monitored to allow the complex Young’s modulus and the complex Poisson’s ratios to be calculated. It was found that the complex Young’s modulus and the complex Poisson’s ratios were very close in the Black Diagrams, but diverge sharply in the Cole–Cole plots. It was observed that the maximum difference between the complex Poisson’s ratio in direction 2 and direction 3 is less than 0.05. It would appear that this difference is more related to measurement deviation than anisotropy of the material. Some differences were observed in the master curves of complex Young’s modulus and complex Poisson’s ratio obtained from the five laboratories; however these differences could in most cases be explained by temperature differences. It was concluded that within the linear viscoelastic range (small strains) the results from the different laboratories show similar rheological behavior and the material response follows the same trend.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/233433 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
Characterization of the three-dimensional linear viscoelastic behavior of asphalt concrete mixtures
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: GRAZIANI, Andrea; CARDONE, Fabrizio; VIRGILI, AMEDEO
Classificazione: 1 Contributo su Rivista
Abstract: Mechanistic-empirical pavement design methods typically require the identification of the complex Young’s modulus and Poisson’s ratio for the characterization of bituminous layers. However, since in small deformation the frequency-dependent shear and bulk responses of an isotropic body are decoupled, the complex shear and bulk moduli are generally considered fundamental response functions. The objective of this study was to perform the experimental characterization of the three-dimensional response of asphalt mixtures in the linear viscoelastic domain, through the simultaneous measurement of the complex moduli E⁄, K⁄ and G⁄ and the complex Poisson’s ratio m⁄. The testing program consisted of cyclic compression and cyclic tension–compression uniaxial tests on cylindrical specimen, with the measurement of both axial and transverse strain. In particular, frequency sweeps were carried out at temperatures between 0, and 40 C and at axial strain levels between 15 and 60 le. Experimental results highlighted that, for the tested mixture, the time–temperature superposition principle was applicable to both the bulk and shear response, and consequently to the axial response. E⁄ and G⁄ showed very similar trends in terms of both stiffness moduli and loss angle, whereas K⁄ values highlighted smaller frequency dependence. The time–temperature superposition principle was also applicable to m⁄ whose master curves can be qualitatively described using the local approximation to the Kramers–Kronig relations. Results suggest that the simultaneous assessment of bulk and shear response may be a useful tool for the performance characterization of asphalt mixtures.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/229800 Collegamento a IRIS

2016
The effect of curing on the mechanical behavior of cement-bitumen treated materials
RILEM Bookseries - 8th International RILEM Symposium on Testing and Characterization of Sustainable & Innovative Bituminous Materials
Autore/i: GODENZONI, CARLOTTA; CARDONE, Fabrizio; GRAZIANI, Andrea; BOCCI, MAURIZIO
Editore: Springer Science + Business Media
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The re-use of pavement materials is an efficient and cost-effective solution in road rehabilitation and construction activities, especially when the availability of high-quality virgin aggregates is limited. In this context, cold recycling of bituminous pavements is becoming one the of most attractive and low environmental impact techniques. The use of cold-recycled pavement mixtures requires a careful assessment of their mechanical properties, which are influenced by both compositional and environmental factors. In particular, regardless of aggregate nature, binder type and dosage, a distinctive feature of cold recycled mixtures is the requirement for a certain curing period to develop the ultimate values of strength and stiffness. In this study, the mechanical behaviour of cement-bitumen treated materials (CBTM), containing high percentage of reclaimed asphalt (RA), was evaluated considering the influence of curing time and temperature. Two CBTM containing 1.0 and 2.5 % cement and 2.0 % of fresh bituminous binder were analyzed. Cylindrical specimens were compacted using a gyratory compactor and cured at 25 and 40 °C; moisture loss and indirect tensile strength (ITS) were measured at increasing curing times. Results showed that the curing temperature and time (curing conditions) significantly affect the moisture loss by evaporation that therefore can be considered a good estimator of the curing process. Moreover, the mechanical characterization indicated that the moisture loss and the cement content control the increase in strength properties of the investigated CBTM. Results also showed that the cement content strongly affects the moisture loss in addition to assure improved mechanical behavior.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/228647 Collegamento a IRIS

2016
Early age evolution of rheological properties of over-stabilized bitumen emulsion-cement pastes
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Garilli, Erika; Autelitano, Federico; GODENZONI, CARLOTTA; GRAZIANI, Andrea; Giuliani, Felice
Classificazione: 1 Contributo su Rivista
Abstract: This paper focuses on the early age evolution of consistency and rheological properties of fresh bitumen emulsion-cement (BEC) pastes. The tested BEC pastes were fabricated using a Portland limestone cement and an over-stabilized bitumen emulsion and were characterized by water to cement ratio ranging between 0.33 and 1 and by bitumen to cement ratio ranging between 0 and 1. The testing plan included the measurement of sedimentation tendency, setting time and evolution of viscosity with increasing stor- age time. Rheological measurements were also carried out on bitumen emulsion-filler mastics prepared with a reference filler. Results showed that, regardless of water content, the initial and final setting time of BEC pastes increased when the proportion of bitumen with respect to cement was increased. When the total concentration of the dispersed phases was low, the increase in bitumen concentration with respect to cement led to a reduction in the rate of viscosity increase with storage time; on the other hand, when the total concentration of the dispersed phases was high the increase of storage time led to a change in the physical state of the pastes (from fluid to plastic) due to coalescence of bitumen droplets.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/238165 Collegamento a IRIS

2016
Volumetric properties and influence of water content on the compactability of cold recycled mixtures
MATERIALS AND STRUCTURES
Autore/i: Grilli, Andrea; GRAZIANI, Andrea; Bocci, Edoardo; BOCCI, MAURIZIO
Classificazione: 1 Contributo su Rivista
Abstract: Volumetric characteristics significantly influence the mechanical performance and the durability of bituminous mixtures. Indeed, they are important parameters to be considered in both mix design and quality control phases. Nowadays, among compaction methods, the gyratory compactor (GC) is worldwide used for bituminous mixtures. Even if there is not a universally accepted compaction procedure for cold recycling, numerous universities and road administration agencies have employed the GC especially for bituminous emulsion treated materials. However, the presence of recycled aggregate, cement, bituminous emulsion and water requires adapting the traditional volumetric parameters to these recycled materials. This paper describes the volumetric characteristics of cold recycled mixtures based on the traditional principles used for hot bituminous mixtures. In particular, the compactability and the influence of water content on a mixture containing 50 % of reclaimed asphalt stabilized with 3 % of emulsion and 2 % of cement were investigated. Moreover, closed and slotted moulds were used to study in depth the saturation process. Results showed that specimens compacted in a closed mould, at high water contents, have a bi-linear evolution of the voids content, which defines two compaction phases. In addition, laboratory compaction using a closed mould seems to simulate better the full-scale compaction procedure. Finally, the water content that allowed the saturation state to be reached at the end of the compaction process corresponded to the optimum water content of the mixture.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/233432 Collegamento a IRIS

2016
The Influence Mineral Additions on the Failure Properties of Bitumen Emulsion Mortars
8th RILEM International Conference on Mechanisms of Cracking and Debonding in Pavements
Autore/i: Godenzoni, Carlotta; Graziani, Andrea; Corinaldesi, Valeria
Editore: Springer Netherlands
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The use of both cold asphalt and cold recycled asphalt mixtures produced with bitumen emulsion is constantly increasing. The failure properties of these low-energy materials are normally improved by using mineral additions or active fillers. These additions are a key component of the bituminous mortar, which binds the coarse aggregate fraction of the mixture. The objective of the present study is to investigate the evolution of the failure properties bitumen-emulsion mortars obtained by using three different types of additions: Portland cement (active filler), hydrated lime and calcium carbonate (inactive filler). The mortars were prepared with standard sand and a fixed bitumen/addition rate. Cylindrical samples were compacted with a shear gyratory compactor, the selected procedure also allowed evaluating the effect of the different additions and water content on workability. The indirect tensile strengths were measured after 7, 14, 28 and 100 days of curing in two conditions: sealed (i.e. no evaporation) and unsealed, at 50% relative humidity. Each bituminous mortars was also characterized in terms of low temperature fracture resistance. Results showed the influence of the mineral additions on the emulsion breaking and the different curing conditions allowed highlighting the impact of both evaporation and cement hydration on strength and stiffness evolution.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/240145 Collegamento a IRIS

2016
Tests campaign analysis to evaluate the capability of fragmentation test to characterize recycled asphalt pavement (RAP) material
RILEM Bookseries
Autore/i: Perraton, D; Tebaldi, G.; Dave, E.; Bilodeau, F.; Giacomello, G.; Grilli, A.; Graziani, A.; Bocci, M.; Grenfell, J.; Muraya, P.; Pasetto, M.; Kuna, K.; Apeagyei, A.; Lo Presti, D.; Airey, G.; Jenkins, K.; Hajj, E.; Hugener, M.; Marsac, P.
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Cold and hot recycling of reclaimed asphalt pavement (RAP) is increasingly gaining in popularity worldwide due to the need to increase the sus- tainability of asphalt pavement, both from environmental and economic perspec- tives. Despite the increasing of use of these techniques, we are still faced with the problem of correctly characterizing RAP. In the framework of the RILEM TC 237-SIB TG6, a Round Robin Test (RRT) was performed in order to evaluate the capacity of the fragmentation test to characterize RAP materials. A total of 5 laboratories located in 4 different countries were involved in the testing program. This paper focuses on the presentation of the fragmentation test method and the results of the RRT performed on different sources of RAP. To differentiate RAP materials in terms of size alteration vulnerability, fragmentation tests were per- formed at three different temperatures (5, 20 and 40 °C) on different sources of RAP. Fragmentation testing consists in evaluating the amount of materials passing through a control sieve of a coarse uniform RAP material after a fixed series of strokes carried out with a normalized falling mass. Results show that fragmentation is reduced when the testing temperature increases. Fragmentation tests performed on natural aggregates indicate that they do not vary with the testing temperature, and such test results are a function of the amount of foreign matter in the RAP. The results also show that the test is suitable for differentiating RAP materials from different sources.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/231120 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 reclaimed asphalt content on the complex modulus of cement bitumen treated materials
Bituminous Mixtures & Pavements VI
Autore/i: Godenzoni, Carlotta; Graziani, Andrea; Bocci, Maurizio
Editore: Taylor & Francis Group, London,
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The objective of this study was to characterize the volumetric and stiffness properties of cold- recycled mixtures treated with bituminous emulsion and cement, produced using different reclaimed asphalt percentages (50%, 80% and 0%). In the first part of the experimental program, volumetric properties and compactability were analyzed using a gyratory compactor. In the second part, the complex modulus was measured by means of cyclic compression tests, on cylindrical specimens. A conventional frequency sweep procedure was followed in a range of service temperatures. The strain level was chosen focusing the attention on the linear domain. The experimental results showed that complex modulus was influenced by frequency and temperature similar to hot mix asphalt. In addition, the time-temperature superposition principle was verified only for the absolute value of the complex modulus but not for its phase angle. Results also showed the influence of bituminous and hydraulic mortars on the rheological response.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/228668 Collegamento a IRIS

2015
Curing and temperature sensitivity of cement–bitumen treated materials
INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING
Autore/i: CARDONE, Fabrizio; Grilli, A.; BOCCI, MAURIZIO; GRAZIANI, Andrea
Classificazione: 1 Contributo su Rivista
Abstract: In the present study, the curing process of cement–bitumen treated materials (CBTM) was investigated by analysing the influence of cement dosage and curing temperature on moisture loss and evolution of complex modulus. Moreover, the study aimed to characterise the thermo-rheological behaviour of cured CBTM. Results showed that moisture loss by evaporation controls the increase in stiffness of the mixtures. However, excessive evaporation can hinder the full potential of the cement hydration process. Results also showed that the quantitative effects of curing time and loading frequency on stiffness can be superposed. Similar to hot-mix asphalt, CBTM showed a viscoelastic and thermo-dependent response. In particular, results suggested that at higher frequencies, the iso-thermal viscoelastic response is mainly affected by the aged binder whereas, at lower frequencies, the response of the mixtures depended mainly on the behaviour of the fresh binder
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/201504 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
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
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

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
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
Cyclic Approach to Airport Pavement Management Based on Non-Destructive Deflection Testing
ADVANCED MATERIALS RESEARCH
Autore/i: Graziani A.; Grilli A.; Miconi D.; Godenzoni C.
Classificazione: 1 Contributo su Rivista
Abstract: The Authors describe the role of non-destructive deflection tests in Airport Pavement Management System (APMS) presenting the experience developed at an Italian Airport. An original approach to APMS implementation is illustrated, based on the PDCA cycle for quality control and continuous improvement of processes. An example application for the management of the runway pavement is described. Deflection test results obtained in four tests campaign carried out over a ten years period were globally analyzed to obtain pavement bearing capacity evolution and demonstrate the effectiveness of cyclic approach to pavement management. It is showed that structural evaluation can be an invaluable tool in pavement management and assist planning activities in the medium and long term.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/101262 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

2013
Influence of reclaimed asphalt content on the mechanical behaviour of cement-treated mixtures
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Grilli A.; Bocci E.; Graziani A.
Classificazione: 1 Contributo su Rivista
Abstract: For the rehabilitation of asphalt pavements the upper distressed layers are usually milled before overlaying to eliminate reflection cracking–related problems and to preserve the pavement geometry. This maintenance technique generates a large amount of reclaimed asphalt (RA) as a product of the milling operation. The recycling of RA in cement-treated base and subbase courses represents a valuable solution in terms of technical, economic and environmental ben- efits. However, the influence of RA on the mechanical properties of cement-treated materials (CTMs) is still not completely understood. As a consequence, CTMs using a high content of RA have not yet been widely applied. The present paper shows the findings of an experimental anal- ysis on CTMs including 50% and 80% RA in comparison with the reference CTM consisting of 100% mineral aggregates. In particular, indirect tensile tests and unconfined compressive tests were conducted to evaluate the resistance characteristics of the CTMs. In addition, complex modulus tests and ultrasonic pulse velocity tests were performed to investigate the stiffness properties of CTMs. The investigation shows promising results as regards the use of high percentages of RA in CTMs and offers a substantial contribution for the understanding of the mechanical behaviour of CTMs.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/101263 Collegamento a IRIS

2012
Synthesis of Specimen Preparation and Curing Processes for Cold Recycled Asphalt Mixes
2nd International symposium on asphalt pavements & environment, ISAP TC APE, Fortaleza, Brazil, October 1–3 2012.
Autore/i: Tebaldi G.; Dave E.; Marsac P.; Muraya P.; Hugener M.; Pasetto M.; Graziani A.; Grilli A.; Marradi A.; Wendling L.; Gaudefroy V.; Jenkins K.; Loizos A.; Bocci M.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The process of cold recycling (CR) is becoming method of choice for pavement rehabilitation due to significantly added environmental and economic benefits. Understanding and standardization of specimen preparation and curing processes are critical to replicate field conditions in lab. This paper presents an extensive synthesis of various specimen preparation and curing processes for cold recycled asphalt mixes. Topics synthesized include RAP, emulsion/bitumen and aggregate preparation, mixing processes, pre- and post- compaction curing, compaction and mechanical testing. This paper was developed through efforts of cold recycling task group (TG6) of RILEM Technical Committee on Testing and Characterization of Sustainable Innovative Bituminous Materials and Systems (TC-SIB).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82841 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
Classification of recycled asphalt (RA) material
2nd International symposium on asphalt pavements & environment, ISAP TC APE, Fortaleza, Brazil, October 1–3 2012.
Autore/i: Tebaldi G.; Dave E.; Marsac P.; Muraya P.; Hugener M.; Pasetto M.; Graziani A.; Grilli A.; Marradi A.; Wendling L.; Gaudefroy V.; Jenkins K.; Loizos A.; Bocci M.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/82839 Collegamento a IRIS

2012
Compactability and Thermal Sensitivity of Cement-Bitumen Treated Materials
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Grilli A.; Graziani A.; Bocci M.
Classificazione: 1 Contributo su Rivista
Abstract: Full depth reclamation is one of the most used rehabilitation methods for subbase courses in high-traffic roads. The use of both cement and bituminous binder as binding agents for reclaimed pavement materials can lead to mixtures having high bearing capacity and resistance to permanent deformation, avoiding premature cracking due to shrinkage. This paper focuses on two main topics: compactability and thermal sensitivity of cement- bitumen treated materials (CBTM). Liquid dosage in CBTM is a key parameter in order to obtain an effective compaction. The volumetric characteristics and the optimum liquid content of CBTM were studied by means of two compaction methods: Proctor and shear gyratory compactor. The temperature susceptibility of CBTM can be a valuable factor in both design and construction quality control. The influence of temperature on the stiffness modulus of CBTM was investigated using two testing methods: indirect tensile stiffness modulus (ITSM) and ultrasonic pulse velocity (UPV). While ITSM provided reference modulus values at strain levels and rates typical of traffic loads, UPV was used to estimate the Young modulus at very low strain levels and high frequencies.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/81958 Collegamento a IRIS

2011
INSTRUMENTED TEST SECTION FOR THE EVALUATION OF GEOGRIDS IN ASPHALT PAVEMENTS
CONFERENCE PROCEEDINGS 5th INTERNATIONAL CONFERENCE BITUMINOUS MIXTURES AND PAVEMENTS
Autore/i: Graziani A.; Virgili A.; Belogi L.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/56208 Collegamento a IRIS

2011
A study on the mechanical behaviour of cement–bitumen treated materials
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Bocci M.; Grilli A.; Cardone F.; Graziani A.
Classificazione: 1 Contributo su Rivista
Abstract: Full depth reclamation (FDR) of asphalt pavements has gained general appreciation because of its technical, economical and environmental advantages. Along with FDR, the use of cement–bitumen treated materials (CBTM) rapidly increased over the last 10 years even if the lack of well-established technical specifications and reliable in situ control procedures hinder the cost-effective use of this material. Spec- ifications for CBTM are currently based on experience and do not consider all the relevant parameters that affect the mixture behaviour. In this study the influence of curing conditions, temperature and moisture on the mechanical behaviour of CBTM is investigated. The recycled material was sampled during the FDR operations carried out on the Italian A14 motorway. The effect of curing and temperature on stiffness, and resistance to repeated loading were evaluated using cyclic indirect tensile tests. Moisture susceptibility was assessed by means of indirect tensile strength tests. Results showed a temperature-dependent behaviour of CBTM and allowed to define a simple model to predict the stiffness modulus based on curing time and temperature. In addition, the resistance to repeated loading proved to be a sig- nificant factor for the mechanical characterization of tested materials. Finally, regardless of curing conditions, the mixtures showed good moisture resistance.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39863 Collegamento a IRIS

2010
Adhesive and cohesive properties of asphalt-aggregate systems subjected to moisture damage
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Canestrari, Francesco; Cardone, Fabrizio; Graziani, Andrea; Santagata, F. A.; Bahia, H. U.
Classificazione: 1 Contributo su Rivista
Abstract: The bond strength between asphalt and aggregate plays a fundamental role in evaluating the moisture sensitivity of HMA Mixtures. In this study the effect of water on adhesive and cohesive properties of asphalt-aggregate systems was investigated using a modified version of the PATTI. The device was used to measure the pull-off strength on different asphalt-aggregate combinations and to evaluate the influence of water immersion at two different temperatures. In particular, six asphalt binders were employed in combination with two aggregate types, having different asphalt affinity. The effect of the aggregate surface temperature during specimen preparation was also tested. In the first phase of the study the within-laboratory repeatability of the test procedure was investigated. The results showed the PATTI test is able to evaluate with good precision the pull-off strength and that its repeatability depends on the failure type (adhesive or cohesive). In the second phase of the study a full factorial experiment was employed to verify the reliability of the test for routine use in determining the adhesive and cohesive properties of asphalt-aggregate combinations and the effects of moisture damage. The results showed that, in the dry condition, the test was able to measure the internal cohesion of the asphalt binders. The results also showed the effects of water damage on the pull-off strength and the decisive role of asphalt-aggregate affinity was clearly highlighted. Using wet conditioning of the PATTI samples it was proven that water affects the adhesive bond between asphalt and aggregate much more than the asphalt cohesion. Moreover, the results indicate that aggregate temperature during sample preparation has only a limited effect on the adhesive strength.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50188 Collegamento a IRIS

2009
An Experimental investigation on unbound mixtures containing recycled materials
The Sixth International Conference on Maintenance and Rehabilitation of Pavements and Technological Control
Autore/i: F. SANTAGATA; F. CARDONE; V. PANNUNZIO; A. GRAZIANI
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Conservation of resources, preservation of the environment and the increasing problems connected with the management of landfills are the main issues which developed countries have to deal with. Nowadays, the recycling of waste materials is the most suitable method in road maintenance and rehabilitation. In this context, the present research work focuses on mechanical investigations in order to evaluate the reliability of using waste materials in unbound base and/or subbase layers. In particular C&D and RAP were selected as recycled materials and compared with traditional dense – graded aggregate base coarse. Different recycled blends containing different percentage of C&D and RAP were considered in order to evaluate the effects of the nature and quantity of demolition debris on the bearing capacity of unbound road layers. To that end, a mechanical characterization based on the evaluation of design parameters such as Resilient Modulus and CBR were performed. The experimental results showed that C&D and RAP materials are a sustainable and effective alternative to traditional aggregates for base construction.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52635 Collegamento a IRIS

2009
Evaluation of Runway Bearing Capacity: In-Situ Measurements and Laboratory Tests
Bearing Capacity of Roads, Railways and Airfields
Autore/i: GRAZIANI A.; BARBATI S.; CARDONE F.; SANTAGATA E.
Editore: Erol Tutumluer & Imad Al-Qadi
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: This paper describes the structural evaluation procedure for the new runway pavement of the Ancona Airport in Italy. As part of a major rehabilitation project, 520 m of runway were fully reconstructed along the “keel” section. The new pavement was constructed on a lime-stabilized subgrade. The base course had a lower cement stabilized layer and an upper hot mix asphalt layer. Modified binder was employed in all bituminous mixes, including the SMA wearing course. An extensive experimental program was carried out as part of the construction control activities. Dynamic Cone Penetrometer (DCP), static and light-weight dynamic plate tests were performed to estimate subgrade and foundation stiffness. Global pavement response was evaluated using deflection testing (HWD). A laboratory test program was completed to carefully assess physical and mechanical characteristics of pavement materials. In particular stiffness and fatigue properties of the asphalt layers were evaluated both on cores and laboratory compacted specimens. The analytical evaluation of the pavement strength was carried out using effective material properties for modulus and fatigue. Results were compared with calculations based on conventional FAA criteria. The study confirmed that an enhanced behavior of asphalt mixes, related to the use of modified binder, can be anticipated.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53620 Collegamento a IRIS

2009
L'impiego di conglomerato bituminoso di recupero nelle miscele stabilizzate a cemento
STRADE & AUTOSTRADE
Autore/i: M. BOCCI; A. GRILLI; A. GRAZIANI
Editore: EDI-CEM, Milano
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/39864 Collegamento a IRIS

2009
Interlayer bonding design of porous asphalt course interface
Proceedings of the Sixth International Conference on Maintenance and Rehabilitation of Pavements and Technological Control, MAIREPAV6
Autore/i: CANESTRARI F.; FERROTTI G.; GRAZIANI A.; BAGLIERI O.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: ABSTRACT: Interlayer bonding affects performance of asphalt concrete pavements. In order to guarantee good bonding, tack coats are frequently applied at various interfaces. Interlayer bonding design consists in the determination of the optimum tack coat rate and the ASTRA (Ancona Shear Testing Research and Analysis) test method can be used for this purpose. In this study, the tack coat design of the interface between an existing porous asphalt and a newly laid open graded course was developed. In order to check whether the two porous layers are independent or behave as a Twinlay, the drainability of the resulting double-layered system was also investigated. The ASTRA tests showed that acceptable interlayer bonding results can be obtained for each emulsion rate studied but higher tack coat rates mitigate the scatter of the results. In terms of drainability, the porosity of the existing layer does not increase the drainage characteristics of the double-layered system, for each interface treatment considered.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/50262 Collegamento a IRIS

2007
Experimental characterization of transparent synthetic binder mixes reinforced with cellulose fibres
4th International SIIV congress
Autore/i: F. A. SANTAGATA; F. CANESTRARI; G. FERROTTI; GRAZIANI A.
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The use of synthetic binders in wearing course mixes allows to integrate road pavements into urban surroundings. In fact, the mixes prepared with this binder mitigate the visual impact that common asphalt materials produce, allowing a pavement coloration depending on the aggregate dyes to be obtained. In this paper, the characterization of open graded mixes prepared with a synthetic binder, reinforced or not with cellulose fibres, was performed. In particular, nine mixes, with different binder and cellulose fibre contents, were investigated through several laboratory tests to find the ‘optimum’ mix in terms of both mechanical performance and durability. The study of all mixes was performed in two steps. In the first step, traditional tests were carried out: Marshall, Indirect Tensile and Cantabro tests. Moreover, to investigate the water effect on these open graded mixes, the traditional tests were also performed on specimens immersed in water for 15 days, and the results were compared. In the second step, the same nine mixes were investigated in terms of rutting behaviour by using Wheel Tracker Machine, and stiffness modulus and fatigue strength through Nottingham Asphalt Tester (NAT). Finally, the comparison with a traditional open graded mix (with SBS hard bitumen) was performed showing higher laboratory performance for the synthetic binder mix. This paper shows that specific synthetic binder and cellulose fibre contents provide an ‘optimum’ open graded mix.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52988 Collegamento a IRIS

2006
GPR investigation for the optimization of runway maintenance
Second International Airports Conference: Planning, Infrastructure & Environment
Autore/i: E. SANTAGATA; S.D. BARBATI; A. GRAZIANI
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: The Authors present the results obtained during the experimental investigations carried out to support the design of rehabilitation works on runway 04-22 of the “Raffaello Sanzio” Airport of Falconara (Ancona), Italy. Due to the lack of detailed technical information on the existing pavement, it was considered essential to perform both intrusive (coring, Dynamic Cone Penetrometer) and non-intrusive (Heavy Falling Weight Deflectometer, Ground Penetrating Radar) field tests. Among the others, GPR data were especially useful. They were employed to build a complete 3D mapping of the runway, the results of which matched extremely well with those of other investigations and with the historical data available in the airport. Furthermore, GPR data allowed the Authors to carry out a detailed analysis of the structural behavior of the pavement according to a conventional back-calculation approach based on the definition of homogeneous sections and by following a more refined procedure based on single-point measurements. Along the runway it was possible to isolate zones characterized by the presence of different pavement types and by a corresponding variation of structural performance. As a consequence, the design of maintenance works was fine-tuned in order to remain within the allocated budget while still guaranteeing the required levels of expected performance.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49405 Collegamento a IRIS

2003
La tecnica della simulazione statistica applicata allo studio teorico ed alla progettazione delle intersezioni stradali
Autore/i: A. Virgili; G. Cerni; F. Cardone; A. Graziani
Classificazione: 5 Altro
Abstract: Atti del CIRS, Centro Sperimentale Interuniversitario di Ricerca Stradale, Gennaio 2003.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/71099 Collegamento a IRIS

2003
Qualifica prestazionale di un misto granulare di riciclo finalizzata al progetto di pavimentazioni industriali in calcestruzzo
Autore/i: F. SANTAGATA; GRAZIANI A.
Classificazione: 5 Altro
Abstract: Atti del convegno internazionale VARIREI 2003 “Valorizzazione e riciclaggio di rifiuti industriali”. L’Aquila, 23-26 giugno 2003.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/52285 Collegamento a IRIS

2003
Applicazione di un modello di simulazione alla progettazione della corsia di accelerazione
Atti del CIRS, Centro Sperimentale Interuniversitario di Ricerca Stradale
Autore/i: BAGLIERI O; GRAZIANI A; TORALDO E; A. VIRGILI
Classificazione: 5 Altro
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49512 Collegamento a IRIS

2002
Formulazione generale dei raccordi plano-altimetrici definiti sulla base del comportamento dell’utente
Atti del XII Convegno Internazionale SIIV
Autore/i: CANESTRARI F; GRAZIANI A; A. VIRGILI
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: SIIV - XII Convegno Internazionale: Riqualificazione funzionale e sicurezza del sistema viario. Universita' degli studi di Parma
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/53399 Collegamento a IRIS

1998
Effetti dell'invecchiamento sull'adesivita' dei bitumi stradali
Autore/i: M. BOCCI; G. CERNI; A. GRAZIANI
Classificazione: 5 Altro
Abstract: ADEGUAMENTO FUNZIONALE E MANUTENZIONE DELLE INFRASRUTTURE VIARIE ATTI DEL VIII CONVEGNO NAZIONALE SIIV POLITECNICO DI MILANO, 19-20 OTTOBRE 1998
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49402 Collegamento a IRIS

1996
La Regolarità delle Pavimentazioni Stradali - Confronto tra un approccio deterministico (IRI) ed uno probabilistico
I MATERIALI NELLA SOVRASTRUTTURA STRADALE ATTI DEL VI CONVEGNO SIIV
Autore/i: A. GRAZIANI; BOCCI M
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: I MATERIALI NELLA SOVRASTRUTTURA STRADALE ATTI DEL VI CONVEGNO SIIV Facoltà di Ingegneria, Ancona 14-16 Ottobre 1996
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/49401 Collegamento a IRIS




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