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Abstract
The experimental and discrete element method was used to investigate the interaction between concrete-gypsum interface and internal notch. Gypsum and concrete semi-circular samples with diameter of 10 cm and height of 10 cm were prepared separately. Then one gypsum sample and one concrete sample was attached to each other with glue. The middle space between gypsum–concrete interface has not any glue so one joint was built in this space. The length of joints were 2 cm, 4 cm, and 6 cm. In experimental tests, the joint direction related to loading axis change from 0° to 90° with increment of 30°. Totally, 12 experimental tests were performed. In numerical tests, the joint direction related to loading axis change from 0° to 90° with increment of 15°. Totally, 21 numerical tests were simulated. This testing show that the failure process is mostly governed by the joint direction related to loading axis. The tensile strengths of specimens are related to the fracture pattern and failure mechanism of the discontinuities and gypsum–concrete interface direction. The tensile behavior of discontinuity is related to the number of induced tensile cracks which are increased by decreasing the joint length. The tensile strength of samples decreases by increasing joint length. Their value was minimum when joint angularities were 30° and 45°. Failure pattern and failure strength are similar in both of the experimental test and numerical simulation.