Interface shear strength between SCC and carbonated concrete considering different influence parameters

A test was carried out to study the interface shear strength between carbonated concrete substrate and self-compacting concrete (SCC) overlay. One hundred and fourteen Z-type specimens were designed and subjected to direct shear tests. The influence of four interface treatment methods, three strengthening schemes and SCC strength on interface shear strength were discussed. Two coefficients considering the influence of interface treatment method and strengthening scheme on interface shear strength between carbonated concrete and SCC were developed. The results show that interface shear strength is affected not only by SCC strength but also by the strengthening scheme for the same interface treatment method, which increases with the increase of overlay strength for the same interface treatment method and strengthening scheme. The position of groove has little influence on interface shear strength for grooved specimens. Implanting steel bar is the most effective way to improve interface shear strength. When the carbonation time is around 60 days, the interface shear strength is increased by about 17%. The theoretical interface shear strength obtained by the developed model agreed well with tested values. The mean ratio of tested interface shear strength to theoretical strength is 0.86.