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This study examines the strategic incorporation of various recycled materials into asphalt concrete, specifically focusing on municipal solid waste incineration bottom ash (MSWI BA), recycled asphalt shingle (RAS), and recycled concrete aggregate (RCA). Due to the high porosity of MSWI BA and RCA, and the significant asphalt binder content (30–40%) found in RAS, there is a need to increase the amount of liquid asphalt used. RAS is posited as an efficient substitute for the asphalt binder, helping to counterbalance the high absorption characteristics of MSWI BA and RCA. The research objective is to quantitatively evaluate the effect of the combined use of RAS, MSWI BA, and RCA in Hot Mix Asphalt (HMA). This study encompasses several laboratory evaluations (i.e., rutting and tensile strength tests) and a cost–benefit analysis, which is a life cycle cost analysis. The results indicate that the combined use of these materials results in a higher tensile strength and rut resistance when compared with the control (with virgin aggregate). According to the cost–benefit analysis result, when the three recycled materials are used for an HMA overlay over an existing aged pavement, it could be 60–80% more cost-effective compared to a conventional HMA overlay, thereby offering significant economical savings each year in the field of road construction. [ABSTRACT FROM AUTHOR]

This study investigated the positive effect of the combined use of recycled asphalt shingles (RASs) and municipal solid waste incineration (MSWI) bottom ash (B.A.) in asphalt concrete, which contributes to enhanced sustainability in pavement engineering. In addition, unlike traditional approaches that employ individual recycling material in hot mix asphalt (HMA), the combined use of the two waste materials maximizes the mechanical performance of the asphalt mixture. The addition of RAS (with 30–40% aged binder) as an additive generally enhances the strength/stiffness of the asphalt mixture. The high porosity/absorption of MSWI BA results in an additional amount of liquid asphalt binder in the mixture. As an admixture, RAS could supply the additional asphalt binder in the mixture when MSWI BA is used as an aggregate replacement. This research was conducted in two phases: (1) to examine the effect of MSWI BA alone and its optimal asphalt content (OAC), and (2) to assess the combined effect of B.A. and RAS in HMA. Multiple laboratory testing methods were employed for the mechanical performance investigation, including the Marshall stability test, rutting test, and indirect tensile test. The testing results show that the 20% B.A. replacement exhibits the best performance and that it requires an additional asphalt binder of 1.1%. For the combined use of MSWI BA and RAS, 5% RAS shows the best mechanical performance. All mixtures that contain the B.A. and RAS show greater strength than the control specimen (regular HMA). [ABSTRACT FROM AUTHOR]

Reflective Cracking (RC) has been a daunting challenge in pavement maintenance and rehabilitation (M&R), yet, still, after several decades of research, no exclusive solution prevails. Moreover, RC mitigation methods have shown significant variation inin situperformance. Therefore, a technique tailored to select an effective RC mitigation method is essential for the success of pavement M&R. In this study, a life cycle cost (LCC) and multi-criteria decision-making (MCDM) analyses were conducted to evaluate the effectiveness of currently available RC mitigation methods and to select the optimal method for an asphalt concrete overlay above flexible pavements. The MCDM includes three components: LCC, performance, and materials (recyclability). These criteria determine the selection ranking of each RC mitigation method. In addition, the effects of the priority level including cost, performance, and recyclability on the final decision were evaluated by conducting a series of sensitivity analysis under multiple scenarios; therefore, weight combination of the three criteria were recorded to define the measurements affecting the final decision. [ABSTRACT FROM AUTHOR]

Moisture damage and fatigue cracking are the most common defects of Sulfur Extended Asphalts (SEAs). Moisture damage in asphaltic mixtures occurs due to the weak cohesion and adhesion that causes the creation of different forms of pavement defects. Various methods have been employed in order to enhance the asphalt mixture’s resistance to the moisture damage. One of the main methods is the addition of antistriping agents (ASAs) which reinforce the bonding between asphalt binder and aggregates. In this study, a series of laboratory testing has been performed to appraise the mechanical properties and moisture sensitivity of the SEA mixtures modified with ASA. In addition, Googas as a new generation of modified-sulfur-mix additive and ASA (nanotechnology Zycotherm) were employed to make warm-mix asphalt (WMA) specimens, through modification of neat asphalt (PG 64-22). Furthermore, four types of mixtures with different additive proportions, containing ASA and sulfur, were prepared, and the moisture susceptibility, resilient modulus, rutting resistance, and fatigue behavior were measured. Obtained results, demonstrated the improvement of mechanical characteristics due to the implementation of the modified sulfur, exclusively for rutting phenomenon. Moreover, nanotechnology Zycotherm (NZ) as an ASA enhanced the adhesion between aggregates and sulfur-extended asphalt; thus, the resistance of SEAs against moisture damage and fatigue cracking improved. [ABSTRACT FROM AUTHOR]

This paper presents and discusses benefits of nano engineering in asphalt binder and asphalt mixture; mainly the performances of polymer, nanoclay and nanocomposite-engineered asphalt mixtures were evaluated. A 58-10 performance grade conventional asphalt (CA), a base binder, was modified separately with a linear SBS polymer and nanoclay at different proportions. As a result, three modified binders: nano modified asphalt (NMA), polymer modified asphalt (PMA), and nanocomposite modified asphalt (NCMA) were made. These modified binders were used to prepare asphalt mixtures. A laboratory study included characterization of physical, mechanical, and rheological properties and behaviors of the modified binders and the asphalt mixtures were performed. Asphalt binder tests were used for the modified binders while performance tests such as tensile strength, resilient modulus and rutting tests were employed for the asphalt mixtures. Test results have shown that nanoclay can enhance physical and rheological properties of the PMA binder as well as its storage stability. With these enhanced binder characteristics, the asphalt concrete specimens showed an increase of tensile strength and resilient modulus and also improved rutting resistance over conventional asphalt concrete. [ABSTRACT FROM AUTHOR]

Abstract: Polymeric nanocomposites have been widely acknowledged recently. In this study, the effects of nanoclay on two grades of styrene–butadiene–styrene (SBS) modified asphalts, linear and branch, have been investigated. The physical, mechanical and rheological properties of original binder, polymer modified asphalts and nanocomposite modified asphalts have been studied and compared. The results have shown that nanoclay can improve the physical properties, rheological behaviors and the storage stability of the polymeric asphalts. Linear SBS-nanocomposite modified asphalt may form an exfoliated structure, whereas the Branch SBS-nanocomposite modified asphalt may form an intercalated structure, based on the X-ray diffraction (XRD) results. [Copyright &y& Elsevier]

Purpose In Hot Mix Asphalt (HMA) overlays, the existing cracks in the underlying pavements can propagate upward to the new added overlay and may cause Reflective Cracks (RC). These cracks allow water infiltration to the underlying layers and causes further moisture damage as well as weakening the unbound layers. Over the years, several methods have been developed for mitigating the RCs. This study aims to investigate the current reflective cracking mitigation methods and develop a methodology for the selection of appropriate mitigation technique. The developed model is then applied to a case study in the state of Florida. Method To accomplish this goal, a nationwide literature review was conducted to better understand the current in practice methods in the United States. Moreover, a life cycle cost analysis (LCCA) in five different road types was performed to find the annuity of roadway rehabilitation for each of the mitigation methods. The uncertainty in the LCCA results is represented using Exploratory Modeling and Analysis (EMA) method. Then through a Multi Criteria Decision Making (MCDM) model, a stochastic optimization model was developed to find the appropriate reflective cracking mitigation solution under Florida’s climate and road conditions, based on different cost and performance weights. Results Based on the available data for the state of Florida, the LCCA results indicate that the annuity of maintaining the roadway with Fabrics and ISAC are lower compared to other methods. However, the results of stochastic optimization model reveal that while looking at the performance and cost at the same time, different methods would be more feasible. For instance, while the cost of the used method does not matter at all and only performance matters, STRATA® is more probable to be the appropriate mitigation technique. The findings of this research are critical for decision makers to better understand the most cost-effective mitigation technique in different conditions. [ABSTRACT FROM AUTHOR]