Experimental study of waterproof membranes on concrete deck: Interface adhesion under influences of critical factors

Waterproof membrane (WM) has been used as an interlayer between asphalt concrete (AC) overlay and concrete deck of bridges for the purpose of waterproof and interface adhesion. The interface adhesion of WM is affected by a myriad of complicated factors, and thus it is essential to study these influence factors in order to design more reliable materials and structures. Accordingly, this paper investigates the adhesion properties of WM under the influences of critical factors including construction temperature, structure characteristic, material content and use of subcoat. Three representative WM materials were studied: APP-modified-asphalt sheet, self-adhesive rubberized-asphalt sheet, and liquid polymer-modified-asphalt coat. Laboratory test programs of direct shear test, pull-off test and 90° peel test were designed to determine the interface adhesion strengths accounting for the influence factors. Results indicate that adhesion strength increases initially and then decreases with increasing WM material content and surface roughness of concrete deck. The compaction temperature of AC overlay and melting temperature of WM play important roles in forming the interface adhesion. Adding SBS-modified asphalt as a subcoat significantly improves adhesion strength. Material and structural designs considering these critical factors are also discussed.