Design and performance of waterborne epoxy-SBR asphalt emulsion (WESE) slurry seal as under-seal coat in rigid pavement

Abstract Common slurry seal is poor at preventing pumping distress when used as the under-seal coat in rigid pavement. In order to improve the water stability of common slurry seal and reduce the pumping distress in rigid pavement, this paper adopts the method of compositely modified slurry seal using waterborne epoxy resin (WER) and styrene-butadiene rubber (SBR) latex. First, waterborne epoxy-SBR asphalt emulsion (WESE) was prepared and fine-graded WESE slurry seal was designed according to the performance requirements for the under-seal coat in rigid pavement. Then, dynamic water erosion resistance, bonding performance and isolation effect of the WESE slurry seal was analyzed and evaluated via a series of tests. Results showed that the water content, the dosage of WER in the WESE, and the WESE content had an effect on the properties of the WESE slurry mixture. In terms of the fine-graded WESE slurry mixture, the content of water and WESE is recommended to be 8.5% and 13.5%, respectively, by weight of aggregate, and the dosage of WER is recommended to be 3% by weight of WESE. The WESE slurry mixture, especially the fine-graded WESE slurry mixture, showed excellent resistance to dynamic water erosion. Moreover, the bonding performance between the WESE slurry seal and the semi-rigid base was affected by seal gradation, forming temperature and curing temperature. In order to guarantee a good bonding performance, the WESE slurry seal should be designed as a fine-graded mineral aggregate, and it should be formed at 20 °C and cured at no less than 10 °C. The WESE slurry seal showed the best isolation effect compared to both the chip seal and the asphalt concrete seal.