Experimental debonding tests between ancient masonry and cfrp

In structures retrofitted by Fiber Reinforced Polymer (FRP) debonding of the reinforcement is one of the principal failure modes and takes place when the shear capacity is reached and the sheet is detached from the substrate. The load at which debonding occurs corresponds to the maximum value attainable by the system and is strictly related to substrate strength and conditions. These parameters are highly variable in ancient masonry, because of the non standardized clay mixture and manufacturing. In order to better understand the behavior of the coupling FRP-ancient masonry some experimental single-lap shear tests are proposed on both ancient clay bricks and masonry specimens reinforced by carbon fiber composite sheets (CFRP). Using the data acquired during the tests, local bond-slip relationships and pull-out curves were obtained. Moreover, starting from the experimental data, the fracture energy was computed and then compared with the expression proposed by the Italian design code CNR-DT 200, 2004.