193 pubblicazioni classificate nel seguente modo:

Laboratory Investigation on the Use of Geocomposites as Waterproofing Systems for Concrete Bridge Decks
JOURNAL OF MATERIALS IN CIVIL ENGINEERING
Autore/i: Mariani, Eugenio; Ingrassia, LORENZO PAOLO; Spadoni, Sara; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: Water seepage in cement concrete structures is one of the main sources of degradation, especially for concrete bridge decks. Therefore, the protection of these strategic structures is a crucial task for civil engineers nowadays. In this context, this study focuses on the use of geocomposites as waterproofing systems for concrete bridge decks. Four geocomposites with different characteristics were compared based on a dedicated testing protocol. The influence of the concrete surface condition (dry or wet) as well as the type and dosage of the primer was also studied. Multilayered slabs, composed of cement concrete, primer, geocomposite, and asphalt concrete, were prepared in the laboratory. The proposed testing protocol includes four types of tests, i.e., shear bond tests (SBT) with the Leutner device, pull-off tests, binder bond strength (BBS) tests, and watertightness tests. Most configurations exhibited good shear resistance and adhesion properties. In general, the geocomposite type and the primer dosage had a significant influence on the behavior of the system, whereas the concrete condition and the primer type had no statistically significant effect. In most cases, the weak point of the system was the interface between cement concrete and primer or between primer and geocomposite. Finally, all geocomposites successfully passed the watertightness test. The proposed testing protocol can be useful for producers to design and optimize their products as well as for road agencies to prequalify the product in the laboratory on the basis of clear performance-based technical specifications.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325583

Composite fatigue failure of cold recycled material mixtures: new insights into the role of bitumen and cement
MATERIALS AND STRUCTURES
Autore/i: Graziani, Andrea; Spadoni, Sara; Ingrassia, LORENZO PAOLO; Virgili, Amedeo; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: In pavement engineering, cold recycled material (CRM) mixtures allow implementing circular economy concepts by maximizing the reuse of reclaimed asphalt without heating. Along with bitumen emulsion and foamed bitumen, Portland cement is often added to CRM mixtures to improve the field performance. However, the role of cement on the fatigue failure is not sufficiently investigated. The objective of this research is to provide new insights into the fatigue failure of CRM mixtures produced with bitumen emulsion and cement. To this aim, two CRM mixtures prepared with different dosages of cement (1 and 2%) were subjected to uniaxial cyclic tension fatigue tests. Empirical and energy-based failure criteria, originally developed for asphalt concrete mixtures, were used to define the fatigue failure. The results showed that the fatigue failure mechanism of CRM mixtures was of a composite type, affected by both cementitious and bituminous bonds. A new criterion was proposed to identify the failure of the cementitious bonds.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325582

Comparison of energy and environmental performance between warm and hot mix asphalt concrete production: A case study
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Ferrotti, G.; Mancinelli, E.; Passerini, G.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/326971

The use of lignin for sustainable asphalt pavements: A literature review
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Gaudenzi, E.; Cardone, F.; Lu, X.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Nowadays, one of the most interests of modern society is to replace increasingly larger quantities of petroleum derived products, which is a non-renewable source progressively depleting, so promoting both environmental and economic benefits. In this context, the practice to employ renewable sources to replace part of the bituminous materials is an effective approach in pavement engineering. Among different biomasses which are recognized as possible sources mixable with bitumen, lignin can represent a valid material. Lignin is a natural resource commonly deriving from the by-product of the production of pulp and paper industry. It is the secondbmost common biopolymer on Earth and represents a potentially attractive alternative as partial substitute ofbbitumen. However, in order to understand the environmental and technical feasibility of the application of lignin in bituminous pavement applications, a multi-scale approach must be adopted. For this purpose, the paper aims at providing an overview of the use of lignin as renewable source in bituminous binders and mixtures, by investigating chemical, rheological and mechanical properties of lignin modified asphalt materials. Moreover, based on the available literature, field application experiences and Life Cycle Assessment (LCA) analysis are also discussed.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/309790

Investigation of unaged and long-term aged bio-based asphalt mixtures containing lignin according to the VECD theory
MATERIALS AND STRUCTURES
Autore/i: Gaudenzi, Elena; Ingrassia, LORENZO PAOLO; Cardone, Fabrizio; Lu, Xiaohu; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: In the near future, the world of civil and building engineering will be dominated by the advent of bio-materials. Even the road paving sector is involved in the transition towards more sustainable solutions, promoting at the same time environmental benefits and economic savings. Currently, one of the main goals is to ensure that bio-binders offer good performance, at least comparable with that offered by conventional materials. In the last decades, the exponential increase in traffic volumes has led to various types of asphalt pavement distresses, among which fatigue cracking is one of the most common. Within this context, this study presents the characterization of a bio-based asphalt mixture obtained by replacing 30% of bitumen with lignin, which was compared with a reference asphalt mixture containing a plain bitumen characterised by the same penetration grade. Laboratory produced and compacted specimens were subjected to complex modulus and cyclic fatigue tests with the Asphalt Mixture Performance Tester (AMPT). Both unaged and long-term aging conditions were investigated. The tests and the subsequent analyses were based on the simplified viscoelastic continuum damage (S-VECD) approach. Overall, the results showed that the presence of lignin led to a lower aging susceptibility, but also caused a slight reduction in fatigue life due to an increase in the material stiffness. Furthermore, the obtained results confirmed previous findings deriving from the study of the two binders and from the conventional characterization of the same asphalt mixtures as well.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/315989

Performance Analysis of Bio-Based Asphalt Mixtures Containing Lignin
EUROPEAN TRANSPORT/TRASPORTI EUROPEI
Autore/i: Gaudenzi, Elena; Canestrari, Francesco; Lu, Xiaohu; Cardone, Fabrizio
Classificazione: 1 Contributo su Rivista
Abstract: Given the need to promote the circular economy and sustainability, one of the main current trends in road materials construction is to employ industrial residues and by-products deriving from renewable sources as extender, replacement or modifier of bitumen, obtaining the so-called “bio-binders”. As regards, lignin can represent a potentially attractive solution, because it is the most abundant natural biopolymer, available in large quantity and characterized by certain chemical similarity with bitumen. In this context, this study focuses on the evaluation of two dense-grade asphalt mixtures for binder layer made with bio-binders containing two different lignins, as partial replacement of bitumen. A preliminary phase allowed to optimize lignin content (30% by bio-binder weight) based on empirical test (i.e. dynamic viscosity, penetration and softening point tests) with the aim of maximizing the bitumen replacement and at the same time obtaining two bio-binders having a consistency similar to a reference plain bitumen. In the second phase, two bio-based mixtures were produced by using the before-optimized bio-binders in different attempt contents. After mixing, specimens were produced by means of a gyratory compactor at set gyrations. Then, the two lignin-based asphalt mixtures were compared with the reference mixture in terms of workability, Indirect Tensile Strength (ITS) and water sensitivity. Despite the bio-based mixtures revealed a slightly penalized workability, overall results showed that they are characterized by fully comparable performances to the reference one, allowing a reduction of the effective bitumen content.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/306066

Advanced fatigue and rutting characterisation of Polish asphalt mixtures based on the VECD model and viscoplastic shift model
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Spadoni, Sara; Ingrassia, LORENZO PAOLO; Jaskula, Piotr; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: The advanced asphalt mixture performance-related specifications (AM-PRS) recently developed in USA can allow an optimisation of the design process of asphalt pavements thanks to the possibility to fully take into account the intrinsic material properties. In this study, four typical Polish mixtures, i.e. a Stone Mastic Asphalt (SMA) for wearing course, two mixtures for binder course with neat bitumen or Polymer modified Bitumen (PmB), and a mixture for asphalt base course with neat bitumen, were investigated by applying such advanced framework. The fatigue performance was studied through the simplified viscoelastic continuum damage (S-VECD) approach, whereas the rutting properties were assessed through the viscoplastic theory of the shift model. The findings were consistent with the composition of the studied mixtures, demonstrating the reliability and applicability of the AM-PRS even for typical Polish mixtures. Specifically, the high amount of soft PmB made the SMA mixture tough against fatigue cracking, but also more prone to rutting. The two binder mixtures exhibited good performance against both fatigue and rutting, and the polymer modification improved the toughness and increased the stiffness at high temperatures. The base mixture is expected to suffer fatigue cracking more than rutting, likely due to the low amount of bitumen and coarser aggregate gradation. These results can be used in the future for pavement performance predictions with FlexPAVE (TM) software programme to ultimately optimise the design of Polish pavements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325584

Interlayer bonding properties of warm recycled asphalt pavements
EUROPEAN TRANSPORT/TRASPORTI EUROPEI
Autore/i: Ferrotti, G.; Ingrassia, L. P.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The need for sustainable road infrastructures has led to great interest in Warm Mix Asphalt (WMA) technologies, which allow the production, lay-down and compaction of asphalt mixtures at reduced temperatures, about 40 degrees C lower than traditional Hot Mix Asphalt (HMA). The use of WMA ensures lower emissions and is also beneficial in the recycling of Reclaimed Asphalt (RA) deriving from the milling of end-of-life pavements. One of the main concerns regarding WMA is the possible poor adhesion between the pavement layers that could be caused by the reduced working temperatures during the paving operations. However, almost no data are currently available in literature on this aspect, which thus could represent a deterrent to the wide application of WMA by road agencies. In this regard, this paper focuses on the investigation of the interlayer bonding properties of warm recycled asphalt pavements constructed along various Italian motorways and national roads using different WMA chemical additives. The Interlayer Shear Strength (ISS) was measured at different pavement interfaces (wearing-binder, binder-base) and time intervals by testing extracted cores with ASTRA and Leutner equipment. The results show that the interlayer bonding properties of WMA pavements are comparable to HMA pavements and are not affected by the WMA additive type. Moreover, ISS depends on the properties of the tack coat applied between the layers and increases over time due to aging effects, especially when the interface is below an open-graded friction course (OGFC). These findings further encourage the use of WMA as environmentally sustainable technologies for the construction and maintenance of asphalt pavements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/324951

A prediction model for top-down cracking in asphalt pavements with open-graded friction course
TRA Lisbon 2022 Conference Proceedings Transport Research Arena (TRA Lisbon 2022),14th-17th November 2022, Lisboa, Portugal
Autore/i: Ingrassia, LORENZO PAOLO; Virgili, Amedeo; Canestrari, Francesco
Editore: Elsevier
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Thick asphalt pavements with open-graded friction course (OGFC) are subjected to top-down cracking (TDC), a distress consisting of cracks that initiate on the pavement surface close to the wheelpath and propagate downwards. However, road agencies do not yet have adequate tools to predict TDC. The objective of this study was to develop a practical and reliable model to predict TDC depth evolution in such pavements. The proposed model provides a maximum TDC depth that can potentially occur in a pavement characterized by certain mechanical properties and traffic at the time of interest. The model was calibrated and validated considering several Italian motorway pavements affected by TDC based on limited data, therefore more data should be collected in the future. This model can be used in a pavement management system (PMS) to plan timely surface maintenance against TDC.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325613

Determination of equivalent axle load factors with the use of strain energy of distortion
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Rys, D.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The paper proposes a new method for calculation of equivalent axle load factors based on the analysis of strain energy of distortion induced in road pavements by traffic loads. The main advantage of the method is the more accurate calculation of the effects of multiple axles and super single versus dual tyres. The methodconsiders the location of critical points, at which strain energy of distortion reaches extreme values. When single axles are considered, the function of equivalent axle load factor takes on the form of the well-known power equation with the exponent ranging from 2.7 to 5.3. It was proved that the damaging effect of triple axles on asphalt pavement is several times higher than the damaging effect of three single axles carrying the same load, but at a greater distance to each other. Due to this fact, traffic load may be significantly underestimated in many pavement design methods.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295119

Prediction of the Long-Term Performance of an Existing Warm Recycled Motorway Pavement
MATERIALS
Autore/i: Ingrassia, L. P.; Spadoni, S.; Ferrotti, G.; Virgili, A.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Warm mix asphalt (WMA) technologies allow the production, lay-down and compaction of asphalt mixtures at reduced temperatures and the use of higher amounts of reclaimed asphalt pavement (RAP) with respect to conventional hot mix asphalt (HMA), leading to significant environmental benefits and energy savings. However, limited data is available on the long-term performance of such pavements. The objective of this study was to predict the long-term performance of an existing warm recycled motorway pavement (made with WMA mixtures containing RAP) constructed in 2016 in central Italy, along with the corresponding hot recycled pavement (made with HMA mixtures containing RAP). For this purpose, cores were taken from the pavements in 2022 to investigate the binder and base courses through dynamic modulus and cyclic fatigue tests, according to the simplified viscoelastic continuum damage (S-VECD) testing approach. The results of the tests were used to predict the service life of the pavements using two pieces of software, KENPAVE and FlexPAVE, based respectively on the elastic design method and the viscoelastic design method in the presence of damage. The FlexPAVE results indicated that the expected service life of the WMA pavement is much longer than that of the HMA pavement, mainly because the WMA mixtures have better damage properties than the HMA mixtures. Conversely, the KENPAVE simulations predicted a similar service life for the two pavements, highlighting the impossibility of the elastic method to catch the actual contribution of high-performance non-standard materials. The promising outcomes of the FlexPAVE simulations further encourage the application of warm recycled pavements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/311529

Chemical and rheological analysis of unaged and aged bio-extended binders containing lignin
JOURNAL OF TRAFFIC AND TRANSPORTATION ENGINEERING
Autore/i: Gaudenzi, Elena; Cardone, Fabrizio; Lu, Xiaohu; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: The use of alternative renewable sources to totally or partially replace bitumen is one of the most current challenges in the road pavement sector. The growing energy cost and environmental concerns lead to the necessity to find alternative solutions, by supporting at the same time sustainability and circular economy principles. Within this framework, this paper presents the application of a powder lignin, a natural bio-polymer deriving from byproducts of wood pulp and paper industry, to replace part of bitumen. The bituminous blend consisting in 70% of bitumen and 30% of powder lignin (by weight) was made in laboratory through the use of a high shear stirring mixer, and a reference plain bitumen characterized by a similar consistency (i.e., same penetration grade) was used as comparison. Then, an extensive investigation on chemical and rheological properties of the bio-binder is presented. Fourier transform infrared spectroscopy (FTIR), saturates, aromatics, resins and asphaltenes (SARA), bending beam rheometer (BBR), frequency sweep tests and multiple stress creep recovery tests (MSCR) with a dynamic shear rheometer (DSR) were performed. Moreover, unaged, short- and long-term aging conditions were considered. Results indicated that powder lignin dominates the rheological behavior of the bio-binder and, from chemical analysis, it seems that it partially acts as a filler and partially as a binder. This would result in improved performances at both low and high temperatures, leading to a wider temperature range of performance grade (PG). Moreover, despite a stiffening effect is recognized, lignin also offers an antioxidant potentiality, reducing the aging susceptibility of the investigated bio-binder.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325576

Characterization of aged bitumen recovered from in-situ polymer-modified HMA and WMA using advanced technologies
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: D'Angelo, S.; Ferrotti, G.; Oliviero Rossi, C.; Caputo, P.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The growing attention of public opinion towards the environment has prompted, in the last decades, to find eco- sustainable and economic alternatives to the traditional productions of hot-mix asphalt (HMA). Under these auspices, the use of warm mix asphalt (WMA) technology applied to mixtures containing reclaimed asphalt (RA) has grown, also due to the well-proven advantages in terms of plant odor emissions and improved working conditions. In addition, it is now known that the mechanical performance of WMAs is completely comparable, even superior in some cases, to that of HMAs. However, to date, there is no comparison in terms of long-term performance of bitumens used in full-scale pavements laid with the two different technologies. Therefore, the aim of this research is to evaluate the oxidative and rheological state of four bitumens recovered from different layers of a full-scale pavement prepared with WMA and HMA technologies and set up a methodology tool set for investigating the physicochemical properties of bitumens. An in-depth laboratory investigation, carried out through physicochemical and rheological tests, has shown that the bitumens used in WMA mixtures are char- acterized by less oxidation than HMA ones (which are characterized by longer relaxation and glass transition times) and the Styrene-Butadiene-Styrene (SBS) polymers inside them are less degraded and still contribute positively to the rheological response even after five years in service, demonstrating the ability of the chemical additive to act as possible “sacrificial agent”, safeguarding the rheological characteristics of polymer modified bitumens (PMBs).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/324952

Development of an automatic method for the recognition of top-down cracking on asphalt pavements
Proceedings of the 7th International Conference on Road and Rail Infrastructure (CETRA)
Autore/i: Chiola, Davide; Ingrassia, LORENZO PAOLO; Salini, Samuel; Canestrari, Francesco
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Top-down cracking (TDC) is a distress affecting asphalt pavements and consists of longitudinal cracks that initiate on the pavement surface and propagate downwards. Such a distress is critical especially for thick asphalt pavements with open-graded friction courses (OGFC), which are common on motorways and high-speed roads. Nevertheless, many road agencies are not fully aware of the TDC issue yet and thus do not have adequate tools to detect TDC. Within this framework, as part of a larger project, this study proposes an automatic method for the recognition of TDC on the pavement. The tool developed is based on machine learning (ML) algorithms and allows to identify TDC from the analysis of pavement images. The main output provided by this tool is the information on the presence/absence of TDC on the pavement, with the related confidence level. The labeling and training of the algorithm were carried out on images of a significant portion of the Italian motorway network (400 km) that were subjected to a non-automatic visual analysis in a previous phase of the project. The algorithm was then validated considering a further 100 km trial section belonging to the Italian motorway network, from which several control cores were taken. The tool developed has the potential to be used in a pavement management system (PMS) to plan timely surface repairs/maintenance against TDC, especially when combined with a model able to predict TDC depth evolution over time.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325614

Influence of specimen geometry on the complex modulus of cold recycled material mixtures
Proceedings of the 7th International Conference on Road and Rail Infrastructure (CETRA)
Autore/i: Grilli, Vittoria; Spadoni, Sara; Canestrari, Francesco; Graziani, Andrea
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Cold recycling of bituminous pavements is becoming increasingly important because it leads to the reduction of costs of pavement maintenance and to lower pollutant emissions with respect to hot recycling. The stiffness characterization of cold recycled material (CRM) mixtures is essential to predict the stress-strain behaviour of the pavement structure. The present paper describes a laboratory experiment for evaluating the effects of specimen geometry on the complex modulus of CRM mixtures manufactured with bitumen emulsion and cement. In particular, the focus was on cylindrical specimens with diameter of 38 mm, adopted to improve the efficiency of laboratory specimen fabrication. Specimens with three different diameters (100 mm, 75 mm and 38 mm) were obtained by coring samples compacted using a gyratory compactor. Their complex modulus was measured by means of cyclic compression tests, using the Asphalt Mixture Performance Tester. The testing temperatures were 5, 15, 25, 35, 45 and 55 °C and the testing frequencies were 20, 10, 5, 1, 0.5, 0.1 Hz. The tests were carried out after long-term curing in a climate chamber. Results showed that the complex modulus measured on 38 mm specimens, although with a greater dispersion, is comparable to that measured on 100 mm and 75 mm specimens, thus it can be used for evaluating the mechanical behaviour of CRM mixture.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325615

Testing Methods to Assess Healing Potential of Bituminous Binders
RILEM Bookseries
Autore/i: Baglieri, O.; Baaj, H.; Canestrari, F.; Wang, C.; Hammoum, F.; Tsantilis, L.; Cardone, F.
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Despite the fact that ability of bituminous materials to heal damage has been largely studied and that a wide literature is available on this topic, there is still no consensus in the research community on actual factors governing healing process and methods to be used to quantitatively asses healing performance of bituminous materials. In such a context, one of the main objectives of the RILEM Technical Committee 278-CHA is to evaluate the different test methods proposed by various research teams to characterize healing in bituminous materials and come up with clear and concise recommendations regarding the evaluation of healing behavior of bituminous materials in the laboratory. To this regard, an inter-laboratory experimental program has been recently started with the specific purpose of testing a common set of selected bituminous binders by using three different protocols. This paper describes the protocols adopted in the experimental program and reports some preliminary results obtained to date.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295111

Laboratory and field investigation of grouted macadam for semi-flexible pavements
CASE STUDIES IN CONSTRUCTION MATERIALS
Autore/i: Spadoni, S.; Graziani, A.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: Grouted macadam (GM) made of an open-graded asphalt skeleton whose air voids are filled with a cementitious grout, is used as wearing course in semi-flexible pavements. GM stands out for its high stiffness and rutting resistance, as well as for its chemical resistant and jointless surface. Although it could satisfy all the engineering properties requested by ports, airports and industrial pavements, there are still few applications worldwide and the mechanical characteristics have rarely been investigated in depth. The main objective of this paper is to compare the stiffness, fatigue resistance and the cracking propagation resistance of GM mixtures manufactured in the field and in the laboratory. The thermal susceptibility and the ravelling resistance of laboratory specimens were also evaluated. The findings show that the stiffening contribution of the grout improves the fatigue life especially at high deformation levels. However, due to the hardening of the asphalt skeleton caused by the ageing of the bitumen, GM mixture may exhibit a brittle behaviour. Considering the validation and correspondence between laboratory and field results, the data could be useful for establish some analytical pavement design criteria.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295118

A new methodology to assess the remaining service life of motorway pavements at the network level from traffic speed deflectometer measurements
INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING
Autore/i: Canestrari, Francesco; Ingrassia, Lorenzo Paolo; Spinelli, Paolo; Graziani, Andrea
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/306887

Investigation into fatigue life of interface bond between asphalt concrete layers
INTERNATIONAL JOURNAL OF PAVEMENT ENGINEERING
Autore/i: Ragni, D.; Sudarsanan, N.; Canestrari, F.; Kim, Y. R.
Classificazione: 1 Contributo su Rivista
Abstract: A proper interface bond between adjacent asphalt concrete layers ensures the layers to act monolithically to withstand traffic and thermal loading. The presence of a weak interface results in delamination, slippage and fatigue cracks thereby affects the pavement performance; hence, requires careful evaluation. The objectives of this investigation are three-fold. The first objective is to develop a test protocol to investigate the damage characteristics of the interface bond. The proposed test applies a 5 Hz cyclic shear load on a double-layered asphalt concrete specimen using a Modified Advanced Shear Tester at 23°C. The second objective is to determine the effect of interlayer shear modulus on the pavement response of typical pavement sections using numerical simulations. The interface material model property used in this study is a set of arbitrary values that lies within the typical range of interlayer shear modulus values observed during cyclic shear tests. The third objective is to propose a failure criterion for shear fatigue testing that is based on the critical tensile strain obtained during pavement response analysis. The test outcomes show that specimens with a tack coat at the interface exhibit a significant increase in shear fatigue life resistance compared to specimens with no tack coat.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295112

Asphalt Binder Modification with Plastomeric Compounds Containing Recycled Plastics and Graphene
MATERIALS
Autore/i: D’Angelo, S.; Ferrotti, G.; Cardone, F.; Canestrari, F
Classificazione: 1 Contributo su Rivista
Abstract: Polymer-modified bitumens are usually employed for enhancing the mixture performance against typical pavement distresses. This paper presents an experimental investigation of bitumens added with two plastomeric compounds, containing recycled plastics and graphene, typically used for asphalt concrete dry modification. The goal was to study the effects of the compounds on the rheological response of the binder phase, as well the adhesion properties, in comparison with a reference plain bitumen. The blends (combination of bitumen and compounds) were evaluated through dynamic viscosity tests, frequency sweep tests, and multiple stress creep recovery (MSCR) tests. Moreover, the bitumen bond strength (BBS) test was performed to investigate the behavior of the systems consisting of blends and aggregate substrates (virgin and pre-coated). The rheological tests indicated that both blends performed better than the plain bitumen, especially at high temperature, showing an enhanced rutting resistance. In terms of bond strength, comparable results were found between the blends and reference bitumen. Moreover, no performance differences were detected between the two types of blends
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295082

Interlaboratory Test to Characterize the Cyclic Behavior of Bituminous Interlayers: An Overview of Testing Equipment and Protocols
RILEM Bookseries
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

Interlayer bonding characterization of interfaces reinforced with geocomposites in field applications
GEOTEXTILES AND GEOMEMBRANES
Autore/i: Canestrari, F.; Cardone, F.; Gaudenzi, E.; Chiola, D.; Gasbarro, N.; Ferrotti, G.
Classificazione: 1 Contributo su Rivista
Abstract: Geocomposites are extensively used in asphalt pavements as they provide significant long-term pavement benefits. Indeed, when correctly installed, geocomposites enhance road pavement performance thanks to their waterproofing properties, stress absorbing membrane interlayer (SAMI) action and improved mechanical strength of the pavement. Nevertheless, the presence of an interlayer causes de-bonding effects that negatively influence the overall pavement characteristics. This paper presents an experimental investigation aimed at comparing the interlayer bonding characteristics of four different geocomposites with an unreinforced reference configuration, laid on an Italian motorway section, in which the reinforcement depth and the lower layer surface condition (milled or new) were also varied. Interlayer shear strength (ISS) was measured, on both cores and laboratory produced specimens, through Leutner and Ancona Shear Testing Research and Analysis (ASTRA) equipment. The ISS results showed that geocomposites can be successfully applied directly on milled surfaces. Moreover, the application of a normal stress, as in the ASTRA device, tends to mitigate any difference related to the specimen heterogeneity. Finally, existing laws, which correlate the results obtained with different shear equipment on unreinforced interfaces, were generalized by considering the presence of geocomposites and the corresponding ISS specification limits were proposed for both ASTRA and Leutner test.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295083

Asphalt mixture modification with a plastomeric compound containing recycled plastic: laboratory and field investigation
MATERIALS AND STRUCTURES
Autore/i: Cardone, Fabrizio; Spadoni, Sara; Ferrotti, Gilda; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: The use of recycled plastic in asphalt pavements represents a sustainable and economic choice which, if correctly designed, could significantly improve the resistance against the typical distresses of flexible pavements. For this reason, this paper aims at evaluating the mechanical properties of two asphalt mixtures modified with two plastomeric compounds through the dry method, by comparing their results with those obtained for a reference asphalt mixture modified with Styrene–Butadiene–Styrene (SBS) polymers. One of the compounds consisted of plastomeric polymers, whereas the other was made of recycled plastic and graphene. The experimental program included laboratory tests on shear gyratory compacted specimens and cores extracted from a real-scale field trial. The results showed that stiffness, fatigue and rutting resistance of the two polymeric compound modified mixtures were comparable to those of the reference mixture. Finally, a Falling Weight Deflectometer (FWD) campaign, performed in the field after one year of service life of the pavement, showed a reduced structural response of the sections constructed with compound modified mixtures with respect to the reference one because of compaction issues and possible interlayer de-bonding effects.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/302700

New Habits of Travellers Deriving from COVID-19 Pandemic: A Survey in Ports and Airports of the Adriatic Region
SUSTAINABILITY
Autore/i: Mancinelli, Enrico; Rizza, Umberto; Canestrari, Francesco; Graziani, Andrea; Virgili, Simone; Passerini, Giorgio
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/309833

A semi-empirical model for top-down cracking depth evolution in thick asphalt pavements with open-graded friction courses
JOURNAL OF TRAFFIC AND TRANSPORTATION ENGINEERING
Autore/i: Canestrari, F.; Ingrassia, L. P.; Virgili, A.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/311531

Use of Modified Reclaimed Asphalt in Warm Mixtures
RILEM Bookseries
Autore/i: Ferrotti, G.; Canestrari, F.; Xiaotian, J.; Cardone, F.
Editore: Springer International Publishing
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Warm Mix Asphalt (WMA) has the advantage over conventional Hot Mix Asphalt (HMA) of reducing pollutant emissions and energy costs. The use of WMA technologies can be fruitfully coupled with the addition of Reclaimed Asphalt (RA) improving asphalt mixture performance. However, this aspect needs to be investigated in more detail. In this regard, this paper focused on the optimization and performance investigation of a dense graded modified asphalt mixture for wearing courses, produced with WMA technology and percentages of RA up to 25%. Two WMA mixtures with two contents of RA were prepared by using a chemical additive. The results were also compared with an HMA control mixture produced with a lower RA content. Shear gyratory compacted specimens were used for a series of laboratory tests to evaluate the performance. The study of stiffness, water sensitivity, permanent deformation and fracture characteristics pointed out that appropriately designed WMA mixtures with RA can be produced without penalizing the performance with respect to the control mixture.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295086

VECD analysis to investigate the performance of long-term aged bio-asphalt mixtures compared to conventional asphalt mixtures
ROAD MATERIALS AND PAVEMENT DESIGN
Autore/i: Ingrassia, L. P.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The road industry is seeking solutions to reduce its dependency on petroleum-based products and its carbon footprint. This is leading to increasing interest in the so-called bio-binders, i.e. binders in which bitumen is partially replaced with bio-oils from renewable sources. Fatigue cracking is a major distress for flexible pavements and therefore the fatigue behaviour of innovative road materials (such as bio-asphalt mixtures) must be characterised in a reliable way. Within this framework, this study aims at comparing the fatigue behaviour of a bio-asphalt mixture and the corresponding conventional asphalt mixture. The two mixtures were laboratory-mixed and laboratory-compacted, and the only difference between them was the binder (a bio-binder containing 10% of wood-based bio-oil vs. a conventional bitumen having physical and rheological properties similar to the bio-binder). The mixtures were short- and long-term aged in the laboratory and subjected to complex modulus tests and cyclic fatigue tests. The results, analysed according to the viscoelastic continuum damage (VECD) theory, showed that, after short-term aging, the bio-asphalt mixture may be slightly stiffer and thus more prone to cracking than the control mixture due to a possible over-aging caused by the effects of high temperatures. However, the long-term aging susceptibility of the bio-asphalt mix was found to be less severe as compared to the control mix, leading to fatigue performance benefits in the long term and corroborating the results of previous investigations at the binder level. Overall, these findings further encourage the use of bio-binders as an alternative to traditional asphalt binders.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295116

Long-term performance assessment of a warm recycled motorway pavement
CASE STUDIES IN CONSTRUCTION MATERIALS
Autore/i: Spadoni, S.; Ingrassia, L. P.; Mariani, E.; Cardone, F.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: In the last decade, warm mix asphalt (WMA) technologies have undergone a strong development in the pavement sector. In fact, the reduction of the production and compaction temperatures up to 40 ◦C with respect to the conventional hot mix asphalt (HMA) mixtures has many environmental beneficial effects. However, the long-term field performance of WMA mixtures is still an open issue, especially when they contain reclaimed asphalt pavement (RAP) and polymer modified bitumen (PMB). In this regard, the objective of this investigation was to monitor the performance of a full-scale field trial constructed along an Italian motorway. The field trial included a section constructed with WMA mixtures (produced with a WMA chemical additive) and a reference section constructed with HMA mixtures. The WMA and HMA mixtures had the same composition (i.e., amount of RAP and PMB) and differed only for the temperatures adopted during the production of the mixtures and construction of the sections. Cored samples were taken from the binder and base courses at different times during the in-service life of the field trial (timespan of six years) and subjected to conventional testing as well as viscoelastic continuum damage (VECD) characterization. The HMA mixtures were generally stiffer than the WMA mixtures, likely due to a more marked RAP oxidation during the production and construction phases and a higher in-service ageing rate. On the contrary, the WMA mixtures always exhibited higher fatigue resistance and better homogeneity than the HMA mixtures. Based on these findings, better long-term performance is expected for the WMA section.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/306267

Comparison of asphalt mixtures containing polymeric compounds and polymer-modified bitumen based on the VECD theory
CONSTRUCTION AND BUILDING MATERIALS
Autore/i: Spadoni, S.; Ingrassia, L. P.; Mocelin, D.; Richard Kim, Y.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/311530

Performance assessment of asphalt mixtures produced with a bio-binder containing 30% of lignin
MATERIALS AND STRUCTURES
Autore/i: Gaudenzi, Elena; Cardone, Fabrizio; Lu, Xiaohu; Canestrari, Francesco
Classificazione: 1 Contributo su Rivista
Abstract: Lignin is one of major by-product from wood and paper industry. As natural biopolymer, it could be a valid alternative as bitumen replacement and/or modifier to enhance the relevant performance of asphalt mixtures, promoting concurrently environmental benefits. In this context, the study focused onthe effects of two different binders containing 30% of lignin (by weight) on the mechanical properties of bio-asphalt mixtures. Specifically, two different lignins were blended with two plain bitumens having different consistencies so obtaining two bio-binders with a similar consistency to that of a reference plain bitumen. The two bio-binders and the reference bitumen were used to produce in the laboratory three dense graded asphalt mixtures for binder courses according to the Italian Technical Specifications. The binder-aggregate adhesion, Indirect Tensile Strength, Stiffness Modulus, thermal susceptibility, fatigue resistance, and low-temperature cracking of mixtures were analysed in both unaged and long-term aged conditions. Overall, this investigation demonstrates that bio-mixtures containing lignin offer comparable results to the reference asphalt mixture. Moreover, the bio-asphalt mixtures exhibit a lower thermal susceptibility, as well as lower aging susceptibility. The findings of this research highly encourage the use of lignin as partial replacement of bitumen in asphalt pavements.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/307961

Il Progetto di Ricerca “Warm Asphalt Recycling in Marche” (WARM 4.0)
RASSEGNA DEL BITUME
Autore/i: Canestrari, F.; Cardone, F.; Ferrotti, G.; Spada, A.
Classificazione: 1 Contributo su Rivista
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295115

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

Sustainable performances of small to medium-sized airports in the adriatic region
SUSTAINABILITY
Autore/i: Mancinelli, E.; Canestrari, F.; Graziani, A.; Rizza, U.; Passerini, G.
Classificazione: 1 Contributo su Rivista
Abstract: The aim of the present paper is to evaluate the greenhouse gas savings and economic benefits associated with sustainable water and energy management at six small-to-medium airports in the Adriatic region. All the data were provided by the airport authorities in terms of the consumption of water, electricity, and energy for heating and company-operated vehicles for three years (2016–2018), as well as information about good practices and the sustainable use of water and energy resources. For the water and energy benchmarks, the most plausible predictive variables were selected according to the literature relevant to the environmental benchmarking of airports. The stepwise linear regression method was used to select the most significant predictive variables in explaining the dataset. The airports showed positive steps towards sustainability, such as a higher share of natural gas in the mix of fuel used for heating, and a green electricity tariff. The CO2 emissions and budget related to motor fuels were less than a quarter of the emissions and budget for energy consumption for heating and electricity. To achieve the goal of zero-emission airports, the decarbonisation of motor fuels and transport should follow the actions aimed at increasing energy efficiency and clean energy for heating and electricity.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295117

Influence of geocomposite properties on the crack propagation and interlayer bonding of asphalt pavements
MATERIALS
Autore/i: Spadoni, S.; Ingrassia, L. P.; Paoloni, G.; Virgili, A.; Canestrari, F.
Classificazione: 1 Contributo su Rivista
Abstract: The application of geocomposites as reinforcement in asphalt pavements is a promising solution for the maintenance/rehabilitation of existing pavements and for the construction of new pavements, whose effectiveness strongly depends on the physical and mechanical properties of the geocomposite. This study aims at assessing the influence of four different geocomposites, obtained by combining a reinforcing geosynthetic with a bituminous membrane, on the crack propagation and interlayer bonding of asphalt pavements. First, a laboratory investigation was carried out on double-layered asphalt specimens. The crack propagation resistance under static and dynamic loads was investigated through three-point bending tests (carried out on specimens with and without notch) and reflective cracking tests respectively, whereas the interlayer shear strength was evaluated through Leutner tests. Then, a trial section was constructed along an Italian motorway and a Falling Weight Deflectometer (FWD) testing campaign was carried out. The laboratory investigation highlighted that—as compared to the unreinforced system—the geocomposites increased the crack propagation energy in the layer above the reinforcement from five to ten times, indicating that they can significantly extend the service life of the pavement by delaying bottom-up and reflective cracking. However, they also worsened the interlayer bonding between the asphalt layers (de-bonding effect). The field investigation indicated that all geocomposites decreased the stiffness of the asphalt layers with respect to the unreinforced pavement as a consequence of the de-bonding effect, thus corroborating the laboratory results. Based on the results obtained, it is desirable that the geocomposite possess a high energy dissipation capability and an upper coating ensuring good adhesion between the asphalt layers. The monitoring of the existing trial section in the future will provide useful data on the long-term field performance of reinforced pavements subjected to actual motorway traffic.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/295113

Cellulosic materials recovery from municipal wastewater: from treatment plants to the market
Clean Energy and Resource Recovery: waste water treatments plants as biorefineries
Autore/i: Akyol, Cagri; Eusebi, Anna Laura; Cipolletta, Giulia; Bruni, Cecilia; Foglia, Alessia; Giosue', Chiara; Frison, Nicola; Tittarelli, Francesca; Canestrari, Francesco; Fatone, Francesco
Editore: Elsevier
Luogo di pubblicazione: Amserdam
Classificazione: 2 Contributo in Volume
Abstract: IntroductionCellulose is the most abundant available biopolymer (up to 1011 t/annum production) with a high molecular weight (Kumar et al., 2020 ). Cellulose is a long linear polysaccharide polymer consisting of β-1,4-linked glucose units (C5H8O4)m, and exhibits in structural cell wall tissues of all higher plans and some algae, while some bacteria also excrete cellulose. Considering the increasing demand for lignocellulosic raw materials in a huge number of industries, undervalued side streams with a high potential should be well utilized in order to embrace a more circular economy approach that reduces waste and allows for the continual use and re-use of resources (Keijsers et al., 2013; Puyol et al., 2017). For thousands of years, mankind process cellulose derived from plants in the production of pulp, paper, and derivatives. With the adoption of toilet paper in modern societies, cellulose fibers became a primary insoluble substrate entering wastewater treatment plants (WWTPs). In the last decade, cellulose recovery from wastewater has become a topic of interest which has attracted a remarkable attention leading to considerable investments (Palmieri et al., 2019; Ruiken et al., 2013). By introducing a microsieving (mesh size <350 μm) downstream of the coarse sieving, it is possible to recover the cellulose from cellulosic primary sludge (CPS; Gherghel et al., 2019). In a wastewater treatment scheme, sieving is a mechanical method often used to remove solid particles. A significant part of the sieved material includes cellulosic fibers (approx. 30–50%), which mainly originates from toilet papers (Espíndola et al., 2021) together with a minor contribution of clothes, fruits, and vegetables. This is a very significant amount since approximately 10 kg toilet paper is used on average per person each year. This number varies greatly, and it is location dependent. For instance, the average toilet paper use in the United States is 22.68 kg/capita year, which translates into more than 2 × 104 ton of toilet paper entering WWTPs daily, assuming that at least 90% of toilet paper is flushed after use. Meanwhile, although the annual consumption of toilet paper per capita is considerably lower in China (i.e., 2.9 kg/capita year), the total amount of toilet paper entering WWTPs is also significant because of its vast number of consumers (Li et al., 2020). Recovering and further adding value to these cellulosic fibers can easily contribute to the sustainability of wastewater treatment processes with the possibility of generating new eco-efficient products while requiring less energy and cost for water reclamation (Mussatto and Loosdrecht, 2016). Then, recovered cellulose can be processed into various value added molecules, building bioblocks, bioplastics, and flocculants (Glińska et al., 2020).
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/294041

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

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

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

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

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

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

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

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

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

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

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

Performance Optimization of Warm Recycled Mixtures
Lecture Notes in Civil Engineering
Autore/i: Cardone, F.; Canestrari, F.; Jiang, X.; Ferrotti, G.
Editore: Springer
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Abstract: Warm Mix Asphalt (WMA) technologies are becoming popular due to their ability to reduce mixing and compaction temperatures compared to the conventional hot mix asphalts (HMAs), with remarkable advantages of environment and costs. Moreover, WMA is considered as one of the most promising technology for increasing the re-use of Reclaimed Asphalt (RA) within the mixture although its effectiveness in recycling issues require more dedicated research activities. This paper describes a laboratory investigation aimed at optimizing a dense graded asphalt mixture for wearing course, produced with WMA technology and including up to 30% of RA. WMA mixtures were prepared by using two contents of a plain bitumen, two contents of RA and one chemical additive. A recycled HMA containing lower RA content, according to technical specifications currently applied in Italy, was selected as reference mixture. Strength and stiffness properties, water sensitivity, rutting and cracking resistance were investigated on shear gyratory compacted specimens. The result analysis on stiffness, rutting and fracture properties indicated the possibility to produce suitable WMA mixtures with higher RA contents without penalizing their performance compared to the reference one.
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/287658

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Influence of production temperature and additive dosage on warm mix asphalt performance
Proceedings of the World Conference on Pavement and Asset Management (WCPAM) 2017
Autore/i: Stimilli, Arianna; Frigio, Francesca; Bocci, Maurizio; Canestrari, Francesco
Classificazione: 4 Contributo in Atti di Convegno (Proceeding)
Scheda della pubblicazione: https://iris.univpm.it/handle/11566/325616

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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