Experimental and numerical investigation on I-II mixed-mode fracture of concrete based on the Monte Carlo random aggregate distribution

This paper presents the result of an experimental and numerical investigation on I-II mixed-mode meso-scale fracture behavior of concrete by the Monte Carlo Simulation (MCS) random aggregate numerical simulation method, involving the tests of 6 four-point shear notched concrete beams with different coarse aggregate. Simultaneously, the effects of volume fraction and specific surface area (SSA) of coarse aggregate on fracture characteristics and peak load were discussed at the meso-level. The results showed that the crack growth patterns of four-point bending concrete beams with separate coarse aggregate volume fraction and SSA were basically consistent under the same loading condition. The actual path of fracture propagation is determined by the difference of the aggregate distribution, and with an increase in the volume fraction of coarse aggregate, the fracture surface is rougher, and I-II mixed-mode fracture of concrete required more fracture energy, which is corresponded to a higher peak load. Also, with an increase in the proportion of small size coarse aggregate, the contact surface area between aggregate and mortar increases, and consequently, peak load increased by the proportion of small size coarse aggregate increase.