Bond behavior between concrete substrate and fabric reinforced cementitious matrix composite

The fabric-reinforced cementitious matrix (FRCM) method is a structural strengthening method for RC structures supplementing the shortcomings of the fiber-reinforced polymer method in terms of heat resistance and suitability. As the FRCM is a strengthening method applied to the surface of RC structural members, its strengthening effect is determined based on the bond behavior between structural members and FRCM composites. In this study, six specimens were prepared for a double shear test to identify the bond behavior between FRCM and RC members. The main variables of the specimens were the number of fabric layers and the spacing between the fabrics. All the specimens exhibited the ultimate strength improvement of 61% to 337% compared to the control specimen depending on the number of fabric layers and the spacing between the fabrics, and the failure mode changed fracture after slip of fabric to debonding between the fabrics and cement matrix depending on the number of fabric layers. A bond behavior model is proposed modifying the existing bond mechanism to consider the number of fabric layers and the spacing between the fabrics. It also considers the interaction between the fibers in the weft direction and the cement matrix. The proposed model was validated for evaluating the bond strength of the FRCM with carbon fabric.