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 laboratory tests, on-site temperature monitoring, and finite element method were conducted to study the adhesive behavior of a waterproof adhesive layer (WAL) that is used between a concrete-bridge deck and an asphalt mixture pavement. Firstly, styrene-butadiene-styrene (SBS) modified asphalt, SBS modified emulsified asphalt, rubberized asphalt, and FYT-1 bridge waterproof coating were used respectively as the material of a waterproof adhesive layer, and their shear strength and tensile strength were tested and compared. Then, the sensors were applied to monitor the temperature of pavement. At last, a finite element model of the bridge was developed to analyze the interfacial shear stress and tensile stress in response to vehicle and temperature loading. Results indicate that SBS modified asphalt and rubber asphalt SAMI can be considered as the material of waterproof adhesive layer. The maximum tensile stress appears when the loads move on the pavement surface above the quarter-span, and the maximum shear stress appears when the loads move on the pavement surface at the center of a span. The safety factor (strength/stress) decreases significantly with increasing environmental temperatures. The effects of environmental temperature, spraying quantity of WAL material, and surface roughness on the adhesive strengths were examined. The influences of pavement and WAL thicknesses, and the interface friction were calculated.