Laboratory investigation on high- and low-temperature performances of asphalt mastics modified by waste oil shale ash

The objective of this study was to use two kinds of waste oil shale ash (OSA) as partial replacements of conventional mineral filler for evaluating high- and low-temperature performances of asphalt mastics. First, asphalt mastics with conventional mineral filler replacement by OSA (OSA/MF) of 0, 10, 15, 30% by volume based on filler–asphalt (F/A) ratios of 0.8, 1.1, 1.4 were prepared. Then, based on the measured penetration, softening point and ductility of modified asphalt mastics, the overall desirability analysis was adopted to determine the optimal OSA/MF. Subsequently, the high-temperature and low-temperature properties of asphalt mastics with the optimal OSA/MF were studied through dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. Results indicated that OSA could improve the high-temperature stability but reduces the temperature susceptibility of asphalt mastics, whereas the asphalt consistency is influenced insignificantly. Besides, the high- and low-temperature properties of asphalt mastics could be improved by the addition of OSA and the oil shale semi-coke (OSSC) modified asphalt mastic is slightly better than oil shale fly ash (OSFA) modified asphalt mastic in some aspects. Based on these results, the optimum F/A ratios could be obtained to enhance the high-temperature and low-temperature properties of asphalt mastics.