Bonding Behavior of Wet-Bonded GFRP-Concrete Interface

Abstract

An experimental study was conducted to investigate the interfacial behavior between glass-fiber-reinforced polymer (GFRP) plate and cast-in-place (CIP) concrete placed against this plate—a method known as wet-bonding. The experimental program consisted of 33 single-shear specimens with various initial placement times of concrete, durations of concrete curing, and interface preparations. Control specimens using a conventional dry-bonded technique were also tested. A model was proposed that was able to predict the interfacial ultimate pullout load and local shear stress-slip relationship of a wet-bonded interface with reasonable accuracy. It is shown that (1) wet-bonded interfaces exhibit lower capacity and interfacial fracture energy than dry-bonded interfaces although the load to cause initiation of debonding is not significantly different; (2) the time of initial placement of the CIP concrete onto the wet, set, or cured resin significantly influences the ultimate pullout load and interfacial fracture energy. When initial placement of concrete follows initial set of the resin, at about 30 min, the ultimate pullout load and interfacial fracture energy are greatest; and (3) the nature of the interface also strongly affects the ultimate pullout load and interfacial fracture energy. Specimens in which fine aggregate is spead onto the resin immediately after its placement exhibit improved interface performance. Nonetheless, wet-bonded interfaces do not approach the capacity of conventional dry-bonded interfaces.