Influence of mechanical properties, anisotropy, surface roughness and porosity of brick on FRP debonding force

This paper aims at evaluating how the FRP/brick debonding force is influenced by brick mechanical properties (compressive, tensile and flexural strength) and physical-microstructural properties (surface roughness, porosity, pore size distribution, rate of water capillary suction). The depth of epoxy resin penetration into bricks and the thickness of brick layer detached at the end of bond test were also determined, in order to investigate the role of resin penetration into the brick on the FRP performance. All the tests were carried out on different brick surfaces (namely “bed” and “face”), to account for possible brick anisotropy. The results of the study point out that brick mechanical properties alone are not sufficient to accurately predict the maximum debonding force, but a better estimation can be achieved taking into account also brick surface roughness and resin penetration depth. If brick anisotropy is not considered, in some cases a remarkable overestimation of the maximum debonding force may be found.