Characterization of Early Age Interface Properties of High-Performance Concrete Overlay and Normal Concrete Substrate

The interface bond strength, curling and delamination due to early age volume change are critical for selecting high-performance concrete (HPC) overlays for reinforced concrete bridge decks. In this study, as part of a large scale program for West Virginia Department of Transportation (WVDOT) to develop overlay specifications, four types of HPC overlays was investigated for curling, delamination under volume change and bond strength under tensile load. Two types of specimens were tested: Pre-cracked rectangular prismatic specimens for early age delamination and butterfly notched specimens for bond strength test. The bi-layer specimens were cured and exposed to temperature 35°C and 50% relative humidity. The specimens were monitored for curling at the corners and peripheries. The ultrasonic pulse signals were recorded for evaluation of interface delamination. Results show that the delamination and edge curling depends on overlay types. Silica fume modified concrete with shrinkage reducing admixtures curled and delaminated less than silica fume modified-only overlay. The latex modified and fiber reinforced concrete overlay performed better than silica fume modified-only concrete. The testing method adopted was sensitive enough to evaluate and compare among overlays.