Experimental and numerical evaluation of fiber-matrix interface behaviour of different FRCM systems

Fiber Reinforced Cementitious Matrix (FRCM) composites are a relatively new strengthening system family, whose mechanical behavior is strongly affected by the wide array of possible inorganic matrices and composites fabrics that can be used and coupled together. Structural tests highlighted that global capacity of the system is strongly affected by fabric-matrix adhesion mechanism. In the present paper, the experimental results of tensile and single-lap shear tests, aimed to define mechanical properties of four FRCM types, are discussed and compared. For each system type, the failure modes for both types of test have been physically identified and clarified. The following development of detailed finite element models, carefully reproducing the mechanical behavior of the different layers of the strengthening system, allowed for the proposal of a reliable shear stress-slip relation for the fiber-matrix interface. The experimental outcomes showed the relevant dispersion of the results in terms of performance, effectiveness and failure mechanisms exhibited by the different FRCM types while the numerical interpretation allowed for a better understanding of the reasons and the parameters behind them.