Effect of temperature variations on the bond behavior of FRCM applied to masonry

In the last decades, Fiber Reinforced Cementitious Matrix (FRCM) composites were successfully introduced to repair and strengthen existing masonry structures. The good mechanical performances of these materials determined their efficiency as a strengthening technique; however, their durability is still an open issue. As a matter of fact, FRCM composites may be exposed to a combination of different environmental conditions and, additionally, to temperature variations due to solar radiation. The objective of this research was to study the effects of temperature variations on the bond behavior of a FRCM composite, constituted by a basalt grid and a lime-based mortar matrix, applied to masonry. For this purpose, an experimental investigation on thermally conditioned FRCM-strengthened masonry wallets is presented, in which 14 single-lap shear tests were performed. Before testing, samples were exposed to different target temperatures inside a climatic chamber: 32, 40, 50, 60 and 80 degrees C. Thermocouples were embedded within the FRCM reinforcing layers at two different depths to detect the inner temperature profiles and to control the conditioning process. The single-lap shear tests were then carried out inside the same climatic chamber, while maintaining the target temperature constant. A decrease in terms of peak-axial stress was observed by increasing temperature, along with a progressive change in the failure mode, from fiber rupture outside the bonded area to fiber slippage within the mortar matrix layers.