Experimental Study on Mechanical Performance of Interface between Mortar and Aggregate in Concrete

Marble which has the same surface roughness with aggregates was used to represent the coarse aggregate (cobblestone) in concrete. The specimens for tensile bond strength were made by casting mortar cylinder on the surface of the marble plane, and the pull-out tester was used to test the tensile bond strength between aggregate and mortar. The shear bond strength was evaluated from axial compression tests of the specimens containing an inclined interface between aggregate and mortar. By varying the inclination of the aggregates, the regression equations of the interface under bidirectional strained condition were established. The mechanical models of interface were used at meso-level and the failure process of concrete was simulated using the simulation system developed by the authors. It was shown that more reasonable results can be gained in the simulation by considering the bond strength of interface between aggregate and mortar.