Bond behaviour of deformed bars embedded in RAC

To investigate the bond behaviour between recycled aggregate concrete (RAC) and rebar, this paper considers recycled aggregates (RAs) (RG of grade I and III and RS of grade II), w/c ratios (40% and 50%), and replacement ratios of RAs (0%, 30%, 50% and 100%). The results were as follows: (a) bond stress-slip shows tendencies like those of normal concrete up to a replacement ratio of 50%; (b) shearing stress-strain is influenced by grade and the replacement ratio of RAs; (c) tau(b) is influenced by grade and the replacement ratio of RAs, but at high w/c, tau(b) is not influenced by the quality and the replacement ratio of RAs; (d) tau(b)/root f(ck) is influenced by the w/c ratio; and (e) tau(b) between RAC and rebar is overestimated or underestimated by existing equations. As a result, a new equation (with modification of either the beta value, invariable value or others), or modified development length or lap splice length must be considered.