Mechanical Properties of a Waterproofing Adhesive Layer Used on Concrete Bridges Under Heavy Traffic and Temperature Loading

Based on the data collected from a concrete box girder bridge in Shanghai-Hangzhou Expressway Widening and Rebuilding Project, the on-site temperature monitoring system of pavement, finite element method and laboratory direct-shear and pull-off tests were designed to study the adhesive behavior of a waterproof layer used between a concrete-bridge deck and an asphalt mixture pavement. Firstly, the sensors were applied to monitor the temperature gradient distribution of pavement in consecutive days in winter and summer. Secondly, a three-dimensional, finite-element model was developed to analyze the interfacial shear stress and tensile stress in response to vehicle and temperature loading. Lastly, the shear strength and tensile strength of SBS modified emulsified asphalt, SBS modified asphalt, asphalt-rubber SAMI and FYT waterproof coating respectively used as a waterproof adhesive layer between SMA (Stone mastic asphalt) pavement and bridge deck were tested and compared. Results indicate that the max tensile stress appears when the loads move on the pavement surface above the quarter-span, and the max shear stress appears when the loads move on the pavement surface at the center of a span. By comparing the computational results with test results, the tensile strength of the four alternative waterproofing adhesive layer materials can always be greater than FE analysis results, and the SBS modified asphalt and rubber asphalt SAMI can be primarily considered for the material of waterproof adhesive layer.