Feasibility and performance of recycling reclaimed asphalt pavement using activated rubber pellets through semi-wet process

Activated rubber pellets (ARP), also known as the semi-wet process rubberized asphalt, is a novel type of rubberized asphalt that can be directly added into the asphalt mixture through the dry process but provide superior mechanical performances equivalent to the wet process. In this study, the feasibility of using ARP in the recycling of RAP to improve its overall performance was explored. Through frequency sweep tests of asphalt mortar, the effect of curing time on ARP was first evaluated. Asphalt mixtures containing 30% of in-situ RAP (30%RAP) were prepared with four rejuvenation strategies, including the use of rubberized asphalt of wet, dry, and semi-wet processes, as well as a reference group using an aromatic extract (AE) rejuvenator. The mobilization indexes established based on Fourier transform infrared spectroscopy tests indicated that the blending efficiency of the 30%RAP mixture using ARP was comparable to that using AE and significantly higher than those using dry and wet processes. Based on the results of the indirect tensile asphalt cracking tests and Hamburg wheel tracking tests, it was found that the 30%RAP mixture using ARP presented superior cracking resistance, and its rutting resistance was only second to the 30%RAP using wet process asphalt rubber binder, implying that the sufficient pre-activation of ARP allows the rubber elastomers to exert their merits of elasticity and intermediate-temperature tenacity when mixed with RAP and virgin asphalt binder.