Experimental study of the shear behaviour of concrete-grout-concrete joints

Grouted sleeve connections are currently widely adopted in precast concrete structures. For this kind of connection, there exists a kind of multilayer concrete-grout-concrete joint whose the mechanical behaviour is quite different from that of the new and old concrete interface. Simply following the current bonding theories and conclusions of new and old concrete interfaces will cause uncertainties in the structural analysis and design. In this study, monotonic and cyclic loading tests were both employed to examine the influence of the grouting thickness and the interfacial shear reinforcement ratio on the shear behaviour of this new type of joint. The shear behaviour was also compared with that of the new and old concrete interface. The results showed that the shear capacity of the concrete-grout-concrete joint was lower than that of the new and old concrete interface. Specimens with a thinner grouting layer or with a larger ratio of shear reinforcement have a higher shear capacity. According to the experimental results, the shear transfer mechanism of the concrete-grout-concrete joint was proposed based on the extended friction shear model, and the modified shear capacity calculation model was then established.