Experimental study on the bond behavior of CFRP-grid-reinforced ECC and NC interface

Carbon-fiber-reinforced polymer (CFRP) grid-reinforced engineering cementitious composites (CFRPG-ECC) have been widely used in structural strengthening engineering owing to their excellent capacity for controlling cracking width. Excellent interfacial bond behavior is essential for ensuring cooperative work between CFRPG-ECC and concrete. However, research on the interfacial bond behavior between CFRPG-ECC and concrete is limited. In this study, the improved hinged beam tests were conducted on ten groups to investigate the bonding behavior at the interface between CFRPG-ECC and concrete. Concrete/ECC strength, interfacial bonding dimensions (bonding length and width), and interfacial bonding methods were investigated. Digital image correlation was used to observe the entire process of specimen failure, the results indicating that the specimen with the CFRP grid could effectively delay the cracking of the ECC layer, improve the bearing capacity and realize interface debonding failure. Moreover, the bonding performance of the CFRPG-ECC and concrete interface was analyzed in terms of bearing capacity, strain and shear stress distribution and bond-slip curve. Finally, an analytical model for estimating the interfacial bearing capacity was established, with its predictions consistent with experimental results.