Performance of polymer-reinforced bituminous mixes using recycled coarse aggregate

Abstract

Bituminous mixes prepared using recycled coarse aggregate exhibit inferior characteristics compared to a control mix using natural stone aggregate. This is mostly due to the presence of loose cement mortar in the recycled aggregate. The study reported in this paper evaluated the performances of recycled aggregate mixes using different polymers, including centrifuged latex polymer, crumb rubber powder and polypropylene fibre. The performance of these polymer-reinforced mixes was then evaluated using a retained Marshall stability test, tensile strength ratio test, four-point bending test and wheel-tracking test. The results showed that all polymers improved the performance of the recycled aggregate mixes, making them better than the control mix. Moreover, cost analysis revealed that unmodified, centrifuged latex polymer and crumb rubber powder are more cost-effective than the control mix, whereas the polypropylene fibre mix was found to be expensive in terms of initial cost. Life-cycle cost analysis, however, showed that the fibre mix was also economical over the long run compared to the control mix. Overall, all polymer-modified mixes using recycled coarse aggregate showed better performance and were more cost-effective that natural stone aggregate mixes, meaning they are a viable alternative for road construction.