Optimization and performance evaluation of waterborne epoxy resin modified emulsified asphalt micro-surfacing based on tunnel driving environment

• A new WEREA micro-surfacing mixture based on tunnel environment was designed. • The mechanical property and functional characteristics of optimized WEREA micro-surfacing were investigated. • The micro-mechanism of optimized WEREA micro-surfacing was revealed. • The mechanical experiments were optimized for the tunnel environment. The objective of this paper is to introduce a new micro-surfacing binder of waterborne epoxy resin emulsified asphalt (WEREA) based on real tunnel driving environment and to overcome the limitation of ordinary micro-surfacing for tunnel pavement. The preparation parameters and process of the new WEREA were proposed in detail. Moreover, the adhesion property and micro-mechanism of the new WEREA were investigated by modified water boiling method and fluorescent microscope test. The mechanical properties as well as functional characteristics of WEREA micro-surfacing mixture were studied by cohesion growth test, modified Marshall test, Cantabro test and wet track abrasion test. Among them, the modified water boiling test, cohesion growth test and modified Marshall test were all improved test methods based on the real tunnel driving environment. Results manifested that WEREA can apparently enhance the adhesion between asphalt binder and aggregates, supplying micro-surfacing pavement sufficient resistance on the tunnel adverse conditions. The waterborne epoxy resin (WER) can effectively promote the stripping resistance and water damage resistance of WEREA micro-surfacing. In addition, the effect of tunnel humidity on formation of initial strength is more obvious, thus, proper ventilation and dehumidification equipment can be taken to accelerate the initial strength formation rate of the mixture. This study can serve as a solid base for more efficient utilization of WEREA micro-surfacing in tunnel preventive maintenance.