Study on the influence mechanism of calcium carbonate particles on mechanical properties of microcrack cement

Restoration of cementitious materials using induced calcium carbonate precipitation is a highly anticipated research domain, offering a promising avenue of study within the realm of environmentally friendly methodologies. In this study, the numerical simulation software PFC is employed to simulate internal microcracks within cement stone subject to calcium carbonate remediation. The simulation outcomes unveil the repair mechanism from a microscopic perspective, providing theoretical guidance for indoor experiments. The research results reveal that microcracks detrimentally impact the compressive strength of cement stone, experiencing a drastic reduction of 79.51% at a 6.56% crack rate, reaching merely 6.65 MPa. Calcium carbonate serves to fill, bond, and support the microcracks, retarding crack development and structural deterioration, thereby enhancing the compressive strength of the cement stone. The compressive strength of the cement stone after repair correlates positively with the bonding strength and filling rate of calcium carbonate, while particle size has little effect. The repair effect on small-size microcracks with size of 0.3 mm x 1 mm is better, and large-size microcracks with size of 0.7 mm x 3 mm will have irreversible effects on cement stone. Calcium carbonate particles will play a better repair effect when the filling rate is in rage of 50%- 80%.