The effect of retreated coal wastes as filler on the performance of asphalt mastics and mixtures

Abstract

Numerous studies have been made on the effect of coal wastes (CWs) on asphalt binders and mixtures, while the investigations on the interpretation of this effect are still rare. This study investigated the effect of coal waste ash (CWA, retreated from CWs by reheating) on asphalt mastics and mixtures, and tried to explain this effect from the physical and chemical characteristics of CWA. Firstly, X-ray diffraction (XRD), thermo gravimetric-differential scanning calorimetry (TG-DSC), particle size distribution (PSD), and Brunauer-Emmet-Teller (BET) gas adsorption model were employed to study the differences between CWA and fine limestone powder (FLP); then the effect of CWA on asphalt mastics and mixtures in different mass fractions (20%, 40%, 60%, 80%) to replace FLP as filler were studied; finally, an economic analysis was also discussed. Results show that the physical and chemical characteristics of CWA can significantly affect the performance of asphalt mastics and mixtures by using equal mass substitution method to replace FLP. And the equal mass substitution method should be prudent to apply for the different density substitution. Moreover, test results also show that the factors of CWA affecting asphalt mastics and asphalt mixtures are not always the same.