Aggregate Retention Performance and Bleeding Susceptibility of Reclaimed Asphalt Pavement Modified Chip Seals: A Laboratory Investigation

Abstract

Chip seal construction has received increased attention recently because of rising construction costs and reduced funding for new asphalt pavement projects. The cost and carbon footprint of chip seal applications can be reduced using reclaimed asphalt pavement (RAP). In this paper, the suitability of RAP material for chip seal applications was evaluated through laboratory experiments. Aggregate retention performance and bleeding susceptibility of chip seal samples were investigated using two different aggregate sources and emulsion types. The gradation of the collected aggregates was matched with RAP aggregates using sieving and batching. Modified sweep, Vialit, and pull-off tests were conducted to determine the aggregate retention performance of RAP-modified chip seal samples. To evaluate the effect of RAP on bleeding susceptibility, a Hamburg wheel tracker (HWT) device with a rubber wheel was used. Macrotexture values were measured at specific HWT passes using a laser texture scanner, and the number of passes until chip seal failure was iterated. According to the results, the aggregate retention performance of RAP was found to be comparable with that of natural aggregates when a binder with an appropriate charge was used. RAP material showed higher aggregate retention with the cationic binder compared to the anionic binder. The bleeding test results indicated that RAP is more susceptible to bleeding. Overall, laboratory test results showed that RAP can be a good alternative to virgin aggregate and may reduce the need for virgin binders used in chip seal construction.