Direct shear tests were performed to study the influence of concrete–rock bonds and roughness on the shear behavior of concrete–rock interfaces. The results of these tests show that the shear behavior of concrete–hardrock interfaces depends on the micro-roughness driving the formation of strong concrete–rock bonds and on the macro-roughness accounting for the influence of the surfaces interlocking. Based on this outcome and recent literature, a cohesive frictional model is used to simulate direct shear tests of bonded concrete–granite interfaces with the explicit representation of naturally rough interfaces. The results of these simulations show that the model has good prediction capability compared to the experimental results, opening up the pathway to numerically based robust statistical analysis.

The shear behaviour of bonded concrete-granite joints under constant normal stress conditions is experimentally investigated in this paper. Concrete was prepared following standard mix used in pre-existing dams in France and poured on granite samples with a natural surface roughness. Before the direct shear tests, the joint surfaces were scanned by a laser profilometer to obtain the 3D morphology features. By analysing the shear test results, no direct correlations were found between the shear strength of bonded joints and classical roughness parameter.

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