Adhesion Characteristics of Warm-Mix Crumb Rubber-Modified Asphalt-Steel Slag Interface under Water Erosion

Abstract

In order to study the effect of water erosion on the adhesion characteristics of warm-mix crumb rubber-modified asphalt (WCR)-steel slag interface, hot-mix crumb rubber-modified asphalt (HCR) was used as the control group. The WCR-aggregate interface adhesion model was established based on the surface energy test. According to the surface energy theory, the adhesion work of WCR-aggregate can be used to calculate their contact angle. Then, the permeability work and spreading coefficient of asphalt-aggregate were obtained. Three processes of asphalt wetting aggregate (adhesion wetting, immersion wetting, and extended wetting) and the compatibility of asphalt-aggregate were analyzed. The interfacial pull-out test and freeze-thaw splitting test were also used to further analyze the adhesion characteristics and water stability of asphalt-aggregate under the action of hydrothermal coupling. Finally, the low-temperature beam bending test of warm/hot-mix crumb rubber-modified asphalt mixture was carried out to verify the experimental results of adhesion characteristics of the asphalt-aggregate interface. The results show that with the erosion of water, the adhesion and water stability of the WCR-steel slag interface and the low-temperature crack resistance of warm/hot-mix crumb rubber-modified asphalt mixture gradually weaken. At the same time, the higher the water bath temperature, the faster the asphalt film destruction, the positive effect of the warm agents on asphalt-aggregate adhesion was weakened, and the WCR-steel slag interface adhesion characteristics were better. The experimental results of low-temperature performance also verify the accuracy of the adhesion characteristics of the asphalt mixture. Finally, the correlation analysis revealed that there was a strong correlation between mechanical indexes (the pull-out strength P, the residual strength ratio, the pull-out strength loss rate η) and water stability index (the freeze-thaw splitting strength ratio). All of them could characterize the water stability of the asphalt-aggregate well. Furthermore, the correlation between η and TSR was the highest, so it is more reliable for evaluating the water stability and adhesion of asphalt and aggregate.