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One of the main difficulties with employing recycled asphalt pavement (RAP) in hot mix asphalt (HMA) is bitumen aging; hence, the percentage of RAP in the HMA is limited. This research evaluates the rheological properties of the RAP binder and the performance of HMA containing high RAP content using waste engine oil (WEO) from an Electrical Power Plant as a rejuvenator. The rheological and microstructural properties of the RAP binder and rejuvenated RAP binder were determined in the laboratory. Both the recycled and rejuvenated recycled mixes were tested for Marshall stability, indirect tensile strength, dynamic modulus (E*), and flow number tests. The RAP binder was recovered using two different processes: rotavapor distillation followed by centrifugation (RCRD) and column distillation without centrifugation (RNCCD). The optimal WEO percentages for the RCRD and RNCCD recovery procedures were 0.5% and 3%, respectively. The Marshall test results revealed that adding WEO to the recycled mix enhanced its stability and flow compared to the control mix. The rejuvenated mix containing recovered binder from the RCRD recovery process was found to be better than the rejuvenated mix containing recovered binder from the RNCCD recovery process. The rejuvenated recycled mixes outperformed the recycled mix in terms of moisture resistance, which was evidenced by tensile strength ratio values of 0.88, 0.90, and 0.91 for the control and 0.5% and 3% WEO modified mixes, respectively. Finally, the results of dynamic modulus and flow number testing revealed that the rejuvenated mixes had a modest drop in both the dynamic modulus and flow number compared to the non-rejuvenated mix. [ABSTRACT FROM AUTHOR]

• SEA modified with rPE is sustainable, economic, and ecofriendly alternative. • rPE made SEA stiffer/elastic thus better resistance to rutting/fatigue cracking. • Addition of rPE to SEA improved elastic and viscous properties. This research evaluates the rheological properties of virgin asphalt and sulfur extended asphalt (SEA) modified with two types of recycled plastic waste (rPW). The investigated plastic wastes are the recycled low-density polyethylene (rLDPE) and recycled high-density polyethylene (rHDPE). It also assesses the environmental and economic benefits of recycling such materials. A total of 16 modified binder samples are produced by adding rLDPE and rHDPE modifiers to virgin asphalt and SEA in four different concentrations of 2%, 4%, 6%, and 8% by weight of asphalt. The basic and rheological properties of the virgin and modified asphalts are explored by conventional tests, and advanced rheological tests at different aging conditions. Finally, cost-effectiveness and environmental analyses are conducted. The environmental benefit analysis is performed by comparing carbon and non-methyl volatile organic compound (NMVOC) emission from the various recycled polyethylene (rPE) with the manufacturing process of the same quantities of virgin LDPE and HDPE when used to modify asphalt. The effect of incorporating sulfur into virgin asphalt on the environment is also determined. Results show that modification yields a higher binder complex shear modulus (G*) and a lower loss tangent (tan δ) at all traffic speeds meaning improved rut resistance behavior under heavy traffic loading and high temperature conditions. About 29% reduction in material cost occurs when rPE-modified SEA is used instead of virgin asphalt. The environmental and economic analyses show that using SEA modified with rPE for road construction is an economic, sustainable, and ecological alternative with better performance compared to virgin asphalt. [ABSTRACT FROM AUTHOR]

Currently, sustainable pavement research focuses on modified asphalt binders with self-healing features for achieving durability and safety goals. This study assesses the self-healing behavior of asphalt binders incorporating innovative lab-manufactured hybrid-structured phase change material capsules (HPCMC). The HPCMC, using by-product paraffin oil as a core encapsulated by waste nano-silica fume as a shell, varied in core-to-shell ratios (0.5:1, 1:1, 2:1) and dosages (1 %, 3 %, 5 %, 7 %) by asphalt weight. Morphological, thermal, and chemical characterizations were conducted using scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). Healing efficiency of unaged and short-term aged HPCMC-modified binders was evaluated using SEM and energy dispersive X-ray (EDX) for morphological and chemical analysis. Rheomechanics were examined through rotational viscosity (RV), performance grading (PG), multiple stress creep recovery (MSCR), strain sweep (SS), frequency sweep (FS), linear amplitude sweep (LAS), and linear amplitude sweep-based healing (LASH). Study findings exhibit superior healing in HPCMC-modified binders compared to unmodified ones, particularly at a 3 % dosage and 1:1 core-to-shell ratio in unaged conditions. This study also evaluates healing assessment criteria and validates the self-healing mechanism, indicating significant potential for the proposed approach to revolutionize pavement construction and maintenance. [Display omitted] • Innovative and sustainable self-healing approach through the incorporation of HPCMC to enhance asphalt binder durability. • Synthesis and characterization of HPCMC through morphological analysis, thermal stability, and chemical investigations. • Evaluation of rheomechanical performance and healing efficiency of HPCMC-modified asphalt binders under varied aging states. • Optimization of core-to-shell ratios and HPCMC dosages to maximize healing efficiency and rheomechanical performance. • Validation of self-healing mechanism, proving HPCMC's ability to repair microcracks and boost pavement quality. [ABSTRACT FROM AUTHOR]