Experimental Study on the Shear Strength Between the Steel Bridge Deck and the Asphalt Overlay

Abstract

Abstract A new steel–concrete interface shear (SCIS) test was used for measuring the interface shear strength between the steel bridge deck and the asphalt concrete overlay. This paper describes the test apparatus, specimen preparation, and testing procedure, and illustrates the interface shear strengths determined with the proposed test method. Three factors were investigated: interface type (a layer of epoxy resin tack coat with aggregate chips, a thin layer of epoxy asphalt tack coat, and a thick layer of epoxy asphalt tack coat with aggregate chips), temperature (25°C and 60°C), and normal stress level (0, 0.2, 0.4, and 0.7 MPa). Interface failure criteria and failure patterns are also reported and analyzed. The experimental results show that the SCIS test exhibits good repeatability. The steel–asphalt interface shows strain-softening behavior until it reaches the sliding state. The interface with epoxy resin tack coat provides the highest shear strengths compared to other types of interface. Substrate temperature has a dominant effect on interface shear strength. On average, shear strengths determined at 60°C are about 25 % to 33 % of those determined at 25°C for all interface types. Increased normal stress levels result in increased interface shear strengths. The normal stress effect is more evident at elevated temperature. Three types of interface show different failure patterns: cohesive failures of the epoxy zinc-rich primer, the adhesive failures at the primer–tack coat interface, and the cohesive failure of the tack coat.