Influence of glass-fiber epoxy coating on bond behavior of FRCM systems with different internal and external CMLs

FRCM composite systems display outstanding capabilities for the reinforcement of existing structures. Their modeling is challenging for the numerous damage scenarios and sources of non-linearity; also, test methods for mechanical characterization are still debated. In this study, six different FRCM systems were considered by combining the same glass-fiber textile, dry or epoxy-coated, and three different matrices based on cement, lime, and gypsum binders. The experimental results of the single shear tests highlighted the beneficial effect of the epoxy resin coating that greatly improves the fiber-matrix adhesion capacity in terms of stress, although nullifying the smooth softening behavior, resulting in brittle failure of the textile. Then, an analytical model aimed at calibrating the CMLs and predicting the corresponding global load slip diagram of the six systems is proposed. The assumptions considered are that the internal and external interfaces experience two different shear stress-slip laws and that the brick and both the matrix layers are rigid.