Wheel-tracking performance of recycled concrete aggregate with recycled glass and brick in unbound pavements under elevated loads

Abstract

As natural quarry materials become increasingly scarce and uneconomical, the construction industry has turned to sustainable alternatives such as construction and demolition (C&D) wastes and recycled glass for road construction. The aim of this study was to evaluate the performance of mixtures consisting of recycled glass (RG), crushed brick (CB) and recycled concrete aggregate (RCA) under varied traffic conditions. This assessment was conducted through wheel-tracking (WT) tests under simulated high-traffic conditions, which involved subjecting the mixtures to elevated vertical loads and an increased number of load cycles compared to previous studies. The study revealed that both RCA + 20%RG and RCA + 20%CB blends displayed comparable or slightly greater mean surface deformations than natural crushed rock under default conditions. The default conditions specified by the local road authority include an 8 kN wheel load and 40,000 loading cycles. The study further revealed that both blends displayed a consistent increase in rut depth as the number of cycles increased up to 100,000 while being subjected to a 20 kN wheel load. The maximum rut depth of RCA + 20%RG was close to the lower end of the maximum allowable rut depth range specified by road authorities. This suggests that these blends are at the limits of carrying heavier loads on highly trafficked roads.