Interfacial zone effects of chloride penetration in precast concrete member joints

Abstract

In precast concrete structures, there are several interfacial zones that result from the connection between two adjacent members; these zones are naturally weak with regard to durability. Considering that recent studies have not specifically focused on this issue, the characteristics of chloride penetration in the interfacial zone of joints in precast and post-cast concrete are investigated through long-term erosion experiments in this study, wherein wet–dry cyclic exposure is used to accelerate the chloride penetration. Additionally, three interface roughness values and two durations of erosion are set as the main variables. The results indicate that the chloride content in the interfacial zone is higher than that present elsewhere and this phenomenon is termed the ‘interfacial zone effect’ (IZE). This is mathematically described as a GaussAmp function. The IZEs at 180 d are distinctly lower than those at 60 d. The IZEs are minor for superficial parts, but major for deep parts. Specimens with a moderate roughness have the least IZE, whereas those with lower and higher roughness both have greater IZEs. The mechanism of these laws is also analysed.