Experimental investigation on bond behavior of cement matrix-based composites for strengthening of masonry structures

Fabric-Reinforced Cementitious Matrices (FRCM) have raised a great interest for the external strengthening of historical masonries, representing a valid alternative to fiber reinforced polymers (FRP). As the effectiveness of an external reinforcement firstly depends on the bond performance, this paper presents an experimental investigation, through double shear test, on the bond behavior of cement matrix-based composites reinforced with 3 different textiles: carbon, PBO (polybenzoxazole) and glass. Textiles and matrix specimens were experimentally tested in order to correlate mechanical properties of the constituent materials with the global response of the composites. The results of bond tests highlighted that PBO fiber-based and glass fiber-based composites better exploit the mechanical properties of the textile. Observation of the failure mechanisms highlighted that debonding phenomena occur at fiber/matrix interfaces. Furthermore, the effective anchorage lengths were estimated. The values of fracture energy were determined by a fracture mechanics approach, using the experimental values of debonding loads. Finally, the values of fracture energy were correlated with the mechanical characteristics of the constituent materials.