3D mesomechanical study on the stress failure mechanism of concrete - Taking uniaxial compression as an example

Abstract

The Basic magnesium sulfate cement concrete (BMSCC) exhibits superior performance advantages over Ordinary portland cement concrete (OPC). This study investigates the quasi-static mechanical properties and mesoscopic damage mechanisms of BMSCC40 and OPC40 through a combination of experimental testing and mesoscopic simulation. The results show that BMSCC possesses higher strength and toughness: its uniaxial compressive strength and peak secant modulus increase by approximately 21 % and 14.4 % compared to OPC. The toughness indices I₅ and I₁₀ are enhanced by 9.4 % and 6.16 %. Additionally, the elastic stage in the ascending segment of the normalized stress-strain curve is longer, and the descending segment is more gradual for BMSCC. Mesoscopic analysis of the damage mechanisms using a three-dimensional random aggregate model reveals that cracks in OPC exhibit significant branching, forming secondary cracks and a spatial crack network. When encountering aggregates, the cracks primarily bypass them. In contrast, cracks in BMSCC tend to propagate independently, penetrating through the aggregates and resulting in a smaller overall lateral strain of the specimen.