Experimental study on the bonding between corrosion-damaged stainless steel bars and concrete

In erosive environments, the degradation of reinforced concrete structures is primarily driven by corrosion of the steel reinforcement. This is the case even for stainless steel bars (SSBs), which undergo corrosion under severe conditions. Investigating the bond characteristics between corroded SSBs and concrete is thus crucial. In this work, accelerated electrochemical corrosion tests were conducted on 33 cubic specimens, 18 with SSBs and 15 with ordinary steel bars (OSBs). Central pull-out tests were conducted on these specimens, both before and after inducing corrosion (51 specimens in total), to examine how variables such as bar type, diameter and corrosion level affected the bond properties. The findings revealed two primary failure modes: pull-out and split pull-out. The SSBs displayed a marginally lower ultimate bond strength with concrete than the OSBs. After corrosion, both bond strength and stiffness initially increased but subsequently declined, with the SSBs exhibiting less degradation. Additionally, digital image correlation technology was used to analyse the strain fields on the specimen surfaces. Bond–slip constitutive models for both uncorroded and corroded conditions were developed for SSBs and concrete, and the model calculations closely aligned the experimental outcomes.