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

Stress-transfer mechanisms at the matrix-textile interface mainly drive the mechanical behavior of FRCM composite systems. The test setup to investigate the maximum bearing capacity of an FRCM system is the Single-lap shear Test (SST). Concerning modeling SST, most works are derived from FRP modeling and disregard the role of the substrate and mortar stiffnesses, while a few studies consider the deformability of the external or the internal matrix layer or both. This study employs a Finite Difference Method (FDM) model to evaluate the bond characteristics and load-bearing capacity of several FRCM systems tested under the Single-lap shear Test. The differences in the tested samples concern the application of epoxy pre-coating to the glass fiber textile coupled with a cement matrix. In particular, the textile was coupled to the matrix both as is, i.e., dry, or by applying the epoxy coating and leaving it to dry for 7 days, and then coupling to the matrix or coupling the matrix on the fresh coating. The results of bond tests are employed to back-calibrate the representative CMLs within a mode-II fracture mechanics approach. Then, the global load slip response is predicted using the numerical model, where mortar deformability is considered.