Role of Matrix in Bond Tests of FRCM Systems. Experimental and Numerical Investigations

It is widely acknowledged that the mechanical behavior of FRCM composite systems is mainly driven by the stress-transfer mechanisms at the matrix-textile interface. The most applied test setup to investigate the maximum bearing capacity of an FRCM system is the single-lap shear test (SST). Concerning the modeling of results obtained through SST, most works disregard the role of the substrate and mortar stiffnesses, while a few studies consider the deformability of the external or the internal matrix layer. To characterize the different behavior of the internal and external fiber-textile interfaces, two distinct Cohesive Material Laws (CMLs), within a mode II fracture mechanics approach, are considered, and the values are calibrated based on the experimental outcomes on glass fiber reinforced systems coupled to gypsum, lime, and cement matrices. Then, a Finite Difference Method (FDM) model is implemented to interpret the bond characteristics and load-bearing capacity of the tested FRCM systems. The numerical results obtained considering two different CMLs are compared to the ones obtained with a single CML, i.e., considering that the two interfaces have the same behavior.