Effect of concrete composition on FRP/concrete bond capacity

The bond capacity is considered to be most related to shear softening relation along concrete/FRP interface. In existing models, it is strongly dependent on the compressive (or tensile strength) of the concrete itself However, theoretical analysis indicates that the shear stress distribution along the FRP/concrete interface at ultimate debonding failure is usually dominated by the frictional part, and aggregate interlocking is leading to residual stress. Size and content of aggregates are therefore suspected to affect the interlocking effect. To investigate the effect of aggregates on the bond capacity, ten different compositions of concrete have been used to prepare specimens for the direct shear test. The bond capacity is found to be related to concrete surface tensile strength, and the aggregate content. Based on the results, an empirical expression using neural network is derived to calculate the interfacial fracture energy in the shear test. The bond capacity can then be calculated according fracture mechanics based model. Good agreement has been obtained between the simulation and experimental results