Bond behavior between metallic and non-metallic bars and sustainable concrete: preliminary study

The study presented in the paper deals with the development and the characterization of an innovative shrinkage-compensating high-workability alkali activated slag-based eco-concrete for the repair and strengthening of reinforced concrete (RC) members. Furthermore, after the characterization of developed mixture at both fresh and hardened state, the paper focuses on the bond behavior between the new concrete and metallic and non-metallic (fiber reinforced polymer – FRP) rebars with the aim to: a) identify the main parameters influencing the stress transfer mechanisms at the interface and, b) to evaluate the bond-slip constitutive relationship by varying the steel bar diameter, the bonded length and, in the case of FRP bars, the surface treatment. To this purpose, a wide experimental program was organized which includes more than 100 pull-out tests performed on several types of rebars bonded to the new concrete and the preliminary results are presented here. The bond performance is also examined through a comparison with the results from similar tests performed by employing ordinary Portland cement concrete blocks characterized by equivalent compressive strength and workability class of the innovative green concrete.