Laboratory evaluation of the effect of coal waste ash (CWA) and rice husk ash (RHA) on performance of asphalt mastics and Stone matrix asphalt (SMA) mixture

Current study assessed the performance of mastics and SMA mixture containing coal waste ash (CWA) and rice husk ash (RHA) in different mass fractions (0%, 25%, 50%, 75% and 100%) as a substitution of limestone powder (LP) as conventional filler. For this purpose, the Multiple Stress Creep Recovery (MSCR) and linear Amplitude Sweep (LAS) tests were performed to investigate the rutting and fatigue performance of asphalt mastics with different fillers and concentrations. Moreover, Marshall stability, resilient modulus, dynamic creep, moisture susceptibility, wheel track, Indirect tensile strength tests were implemented to investigate the mechanical performance of mixtures. The MSCR test results revealed that addition of RHA to original binder led to decrease in strain of binder and hence rutting strength of original binder increases at both stress levels. While the CWA additive has adverse effect in comparison with RHA. Based on the obtained results from LAS test, addition of RHA to original binder increase the fatigue life of binder. Adversely, CWA is incapable of improving the fatigue behavior of mastics. Also modification of mastics with SBS improve the fatigue behavior of modified asphalt binders. Results indicated that replacement of RHA by conventional filler enhances the Marshall stability, resilient modulus, rutting properties, moisture resistance and tensile strength of asphalt mixtures. Adversely, the modification of asphalt binder by CWA resulting in reducing the mentioned performance properties of mixtures, except moisture resistance. In general, the obtained results from this study indicated that reuse of RHA and CWA waste materials in north part of Iran where there are lots of RHA and CWA materials especially RHA in pavement engineering, has two main effects. First, reduce environmental problems. Second, enhance the performance properties of mixtures. (C) 2019 Elsevier Ltd. All rights reserved.