Impact of surface roughness on the debonding mechanism in concrete repairs

Abstract

Surface roughness of the existing concrete substrate was considered to have the greatest impact on the bond strength in repair systems. However, the influence of this parameter has been subject for debates in recent years. The effect of concrete surface roughness is not quite clear, nor there exist a clear relation between the surface roughness and the adhesion in multilayer systems. In order to understand and explain this relation, simple numerical experimentation is used. Repair systems with different roughness parameters are simulated in order to get load displacement diagrams and crack debonding propagation. The influence of roughness on the composite response in simulated direct tension, shear and three point bending test using a lattice model, is studied. Results indicate that roughness has different influence on tensile and shear bond strength. In addition, although it seems to have negligible influence on load bearing capacity of the composite system in bending, it enables more monolithic response and slower debonding propagation.