Shear Mechanisms in Fabric-Reinforced Cementitious Matrix Overlays: Experimental and Numerical Investigation

The design of shear strengthening with fabric-reinforced cementitious matrix (FRCM) is currently based on an additive formula where the contribution of the substrate is added to that of the FRCM. This latter, in current regulations, only depends on the strength and equivalent thickness of the fabric, while the contribution of the mortar matrix is neglected. Aiming to evaluate the effective shear capacity of the FRCM material, an experimental setup consisting of an articulated steel frame was designed for testing small-scale squared-shaped samples under ideally pure shear stress loading conditions. The behavior of four FRCM materials obtained with two basalt fabrics embedded in two different mortar matrices was then investigated to highlight the influence of fabrics architecture, matrix properties, and relative interaction. Digital image correlation (DIC) was used for measuring displacements and strains and for detecting the crack pattern of the small-scale specimens, while a micromechanic numerical approach was used to study the fabric-to-matrix shear stress transfer mechanism. The whole experimental and numerical research provides an in-depth comprehension of the shear mechanical response of the FRCM material.