Laboratory investigation on effects of solid waste filler on mechanical properties of porous asphalt mixture

Abstract

The utilization of solid waste materials in pavement construction has become a trend with the increasing awareness of sustainable infrastructure construction. Among them, the use of some powder solid waste as the alternative filler in asphalt mixture has attracted the attention of many researchers. As is known to all, filler plays an important role in the performance of asphalt mixture, and the great difference between solid waste filler and mineral powder will lead to unpredictable performance changes of asphalt mixture. However, the current research on the changes in mechanical properties of asphalt mixture after the use of solid waste filler is very limited, especially for Porous Asphalt (PA) mixture, which undoubtedly hinders the application of solid waste materials in pavement engineering. Therefore, limestone powder and three types of solid waste fillers (fly ash, diatomite, and red mud) were selected to prepare four types of PA mixtures in this paper. Then, Cantabro test, Hamburg Wheel Tracking (HWT) test, Indirect Tensile Strength (ITS) test, Semi-circular Bending (SCB) test, and Fourier Transform Infrared Spectroscopy (FTIR) test were carried out to comprehensively evaluate the raveling resistance, rutting resistance, moisture susceptibility, crack resistance and anti-aging ability of PA mixtures with different fillers. The results showed that fly ash had a positive but not significant effect on the performance of asphalt mixture. Porous fillers like diatomite and red mud significantly enhanced the bonding performance, strength, stiffness, and aging resistance of asphalt mixture due to the super adsorption and hardening effect on asphalt binder. Meanwhile, it was found that red mud had the anchoring and toughening effect with the SBS modifier due to its interparticle pore structure, which was different from the simple hardening and embrittlement effect of diatomite. Also, the selected red mud contained a certain amount of active Na2O, which was unfavorable to the moisture resistance, but still met the specification requirement. This study is of great significance for understanding the influence mechanism of filler on asphalt mixture and the utilization of red mud waste in asphalt pavement engineering.