Effects of Construction Procedures on Bond in Bridge Decks

The effects of consolidation method and two-course construction on concrete-steel bond in concrete bridge decks are studied as functions of slump, bleed, and depth of slab. The consolidation was varied by vibrator spacing and insertion time. Four top covers were studied: 3/4, 1, and 3 in. monolithic and 3 in. two-course. Bond test specimens were of two types: shallow, with 8 in. of concrete below the reinforcement, and deep, with 24 in. of concrete below the reinforcement. All specimens were modified cantilever beam specimens. Concrete densities were obtained using core samples. Based on the experimental work, high density internal vibration provides improved bond over low density internal vibration. 3 in. monolithic cover provides higher bond strength than 3 in. two-course cover. Increased concrete slump has a negative effect on bond strength for top-cast reinforcement. Deep specimens made with stiff, well consolidated concrete can provide the same bond strengths as shallow specimens