Improved Performance of Asphalt Concretes using Bottom Ash as an Alternative Aggregate

Abstract

Road networks are major infrastructures that support the economic development in both developed and developing countries. Bottom ash (BA) is a by-product from coal-fired powerplants, which is composed of a lipophilic molecule with effective reactivity to bituminous binder. BA was adopted in this research, as a green fine aggregate, to improve the mechanistic performance of asphalt concretes in this research. The effect of BA-replacement ratio (0%, 10%, 15%, 20% and 25%, by total weight of natural fine aggregate) on the Marshall stability and flow, indirect tensile strength (ITS), and mechanistic performance of BA-asphalt concrete, were examined. The mechanistic performance tests included the indirect-tensile condition (indirect tensile resilient modulus (IT Mr), indirect tensile fatigue life (ITFL)) and compressive condition (permanent deformation (PD), rut depth, and skid resistance). BA replacement improves the Marshall stability and flow, strength index, and ITS, up to the optimum BA-replacement ratio, of 5%. The change in IT Mr was found to be linearly proportional to the change in ITS, for all BA-replacement ratios. The ITFL is dependent upon the repeated stress level and can be estimated in terms of IT Mr. For the compressive condition, the PD, rutting, and skid resistances were found to be improved by the BA replacement. The lowest PD and rut depth as well as the highest skid resistance, for IT Mr and ITFL, were found at the optimum BA-replacement ratio, of 5%. The outcome of this research will promote the usage of BA as a cleaner additive in asphalt concrete pavement, which is useful in terms of engineering and environmental perspectives.