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The research focuses on Indirect Tensile Strength variation by changing Height and Diameter of bituminous specimens related to AC16 dense-graded binder course with limestone aggregates and neat bitumen at 4.5% following SUPERPAVE procedure. 70 specimens were prepared by using gyratory compactor by fixing hmin/D ratio equals 0.68. A total of 20 specimens whose diameter is 100 mm were prepared and the other 50 specimens were made according to a 150 mm diameter. Then, 30 of 50 specimens with a 150 mm diameter were cut in two different ways: 10 specimens were cut from the centerline and 20 specimens were cut both from the bottom and upper part to obtain a final height falling a range of 35 and 75 mm in compliance with UNIEN12697-23. Then second step refers to H0 hypothesis test as follows: could ITS values resulting from specimens prepared with 150 mm in diameter and cut by using different procedures be equal to ITS values (mean 3.47 MPa) of specimens prepared with 100 mm in diameter and different height (mean height 69.5 mm) with a significance level of 0.05? The results showed that no statistical difference exists between the 100 mm in diameter specimens and 150 mm in diameter specimens that were cut both from the upper and bottom part. However, in the other scenarios statistical differences were founded. Overall, according to the results it can be concluded that 100 mm in diameter specimens can be used for ITS evaluation of AC specimens instead of 150 mm, which consequently resulted in less materials and simplified lab-scale asphalt manufacturing procedures.

Great efforts have been made in recent years to improve the mechanical properties of asphalt mixtures by replacing conventional mix components with innovative ones or by adding materials such as polymers. Hence, the innovative-sustainable road materials to be investigated through laboratory tests require articulated procedures, the research here presented aims to provide an experimental-methodological approach to analyse the mechanical performance of untraditional hot asphalt mixtures made up using a polymer compound of recycled plastics. Three Asphalt Concrete 20 (AC20) Hot Asphalt Mixtures (HMA) were analysed by measuring base properties (i.e., indirect tensile strength and moisture damage) and advanced features (i.e., stiffness, fatigue, cracking and rutting resistance). As a result, the addition of polymer compound using dry process might lead firstly to change the laboratory mixing procedure than the traditional hot limestone asphalt solutions. The main benefits derived from the adoption of this innovative technology compared to the conventional ones are as follows: a) an improvement of resistance to moisture damage (at 15 °C); b) a suitable stiffness at 10, 20 and 40 °C; c) an increment of the cracking resistance (at 10 °C) and d) a good rutting resistance in terms of rut depth (at 60 °C). .

As a response to the “end of waste” strategy, this study focuses on an innovative laboratory-methodological approach to carrying out measurements for multi-scale characterization of road pavements construction materials; specifically, the engineering performance of sustainable hot asphalt mastics made up using plastic waste as filler was measured to gain a deeper understanding of the physico-machanical performance of traditional and modern mastics, which seriouly affect the design and durability of the final whole road asphalt pavement. Asphalt mastics are bitumen-based materials that give cohesion to the whole asphalt mixture. They consist of filler (with a passing by mass percentage ranging from 70 to 100 for a sieve size of 0.063 mm) and bitumen. Nine asphalt solutions prepared using three percentages of filler content (10, 15, and 20%) by the total weight of neat bitumen whose weight was kept constant were investigated. Firstly, for plastic waste particles, the maximum melting temperature was examined using Differential Scanning Calorimetry, and the phase transitions were subjected to thermogravimetric analysis. The morphology of all the asphalt solutions was then observed using Scanning Electron Microscope, while the advanced rheological properties were measured by means of a Dynamic Shear Rheometer. Cluster Analysis and Principal Component Analysis were performed to aggregate solutions with similar performance within the same group, and, secondly, to provide a small number of uncorrelated explanatory laboratory variables. Three clusters and three Principle Components were found to be perfectly interconnected to describe asphalt mastics performance.

The use of reclaimed asphalt pavement is a practice that is adding significant environmental value to road technologies, not only due to the reduction of materials sent to landfill but also because of the mechanical properties of the reclaimed asphalt (RA) that can be reused. This research focuses on the rheological properties of hot and cold bituminous mastics made up as follows: (1) hot mastics mixed with limestone filler (LF) and bitumen, (2) hot mastics, made from bitumen mixed with jet grouting waste (JW), a mixture of water, cement, and soil derived from land consolidation work in underground tunnels, and (3) hot mastics mixed with LF and JW as filler and bitumen. Three different ratios (0.3, 0.4, and 0.5) of filler per unit of neat bitumen (B50/70) were studied. The same number was used for mixing cold mastics, by using an appropriate laboratory protocol designed since the adoption of a cationic bituminous emulsion. A total of 18 mastics were prepared and investigated. The comparison was carried out using the frequency sweep (FS) test, analysing shear modulus G∗, applying the multistress creep and recovery (MSCR) test (40°C and 60°C) as well as the delta ring and ball (ΔR&B) test, focusing on two main issues: (1) the stiffening effect caused by the filler type used for mixing each mastic, and (2) a comparison, in terms of stiffening effects and nonrecoverable creep compliance (Jnr) of hot and cold mastic performance to highlight JW reuse in mastics. The results showed that the best G∗ performance at test temperatures higher than 30°C is given by cold mastic after 28 days of curing time when JW is added to LF and bitumen. The lowest Jnr value was 40°C and 60°C for the same mastic.

Due to the introduction of secondary materials, the asphalt mixtures to be designed and tested in our laboratories are constantly becoming much more complex than traditional asphalt mixtures making difficult to use conventional laboratory procedure and/or predict expected results. This study proposes a comprehensive characterization of asphalt mixture modified with recycled polymer compound by using both wet and dry process proposing adjustments to laboratory mixing and sample compaction procedure. Accordingly, three AC20 Hot Asphalt Mixture (HMA) were designed and their conventional and performance related properties were assessed by looking at a) Indirect Tensile test (ITS) a) moisture damage by Indirect Tensile strength Ratio (ITSR) test; b) cracking by fatigue and Semi-Circular Bending tests and c) rutting both considering Stiffness Modulus (ITSM) and susceptibility to deform by Wheel Tracker. The results demonstrate that the addition of recycled polymer compounds using dry process might lead to the need to adaptation of the laboratory mixing procedure and the proposed mixing and compaction procedures allowed to engineer a superior recycled polymer modified asphalt mixture manufactured through the dry process, since an increment of mechanical related properties, than traditional asphalt solutions, was exhibited by these modified asphalt mixtures in terms of ITS (+32%), ITSM (11% at 10 degrees C, +18% at 20 degrees C, and +34% at 40 degrees C), rutting resistance (rut depth of 1.86 mm vs 1.92 mm) and fatigue life.

The large amount of plastic waste is currently causing serious pollution to the environment mainly due to long decomposition times and their dispersion. In order to avoid that the pollution by plastics could worsen further, it is trying to encourage companies to recycle existing pallets to create new products. This study investigates the volumetric and mechanical properties of hot bituminous mastics made up using plastic waste materials (PW) as filler. The PW has a maximum size of 2 mm and a melting temperature between 120 and 260 °C. Scanning Electron Microscopy of the PW reveals a mesh structure of elongate elements marked by a much rougher surface than traditional limestone filler (LF). The first step of the study focused primarily on searching for the optimal blending time for the mastics; a total of nine mastics were made up, and no substantial differences were found for any of them on increasing mixing time from 10 up to 60 min in terms of softening point, penetration at 25 °C or dynamic viscosity at 100 °C. Thus, a period of 10 min was selected for mixing all the mastics. The second step focused on the investigation of rheological properties using a dynamic shear rheometer and carrying out a Frequency Sweep (FS) test at temperatures ranging from 0 °C to 50 °C with increments of 10 °C, and a Multiple Stress Creep and Recovery (MSCR) test under 0.1 and 3.2 kPa load levels at temperatures of 40 and 50 °C. The two resulting best solutions are made up of a) 20% PW (HP02), and b) 5% LF plus 15% PW (HLP02), both by the total weight of B5070. Specifically, the shear modulus G* for mastics containing PW showed a distinct increase in G* compared both with B5070 and traditional mastics made up of LF; in particular, the gap becomes more marked moving towards 50 °C, where the best performance of HP02 is obtained. Moving on to illustrate the main results of the MSCR analysis, it was observed that the HP02 and HLP02 solutions showed good recoverable deformation already from the end of the loading phase without waiting for the last step of the unloading cycles at two test temperatures and under two stress levels.