Experimental Study on Static Characteristics of Calcareous Sand Solidified by Nano-SiO₂ Superfine Cement

To study the incorporation of nano-SiO₂ for calcareous sand-super fine cement plus solid static characteristics, nano-SiO₂ and ultra-fine cement were used to replace ordinary portland cement to reinforce calcareous sand. Unconfined compressive strength test and triaxial shear test were designed under different conditions, and the microstructure of samples was observed by SEM to analyze the mechanism of action. The test results show that superfine cement has better reinforcement effect on calcareous sand than ordinary portland cement; there is a critical value for the effect of nano-SiO₂ incorporation on the strength of ultrafine cement, and the strength decreases after the amount exceeds the critical value. In terms of peak strength, peak strain and cohesion, nano-SiO₂ can improve the static characteristics of superfine cement calcareous sand. From a microscopic point of view, it is found that ultra-fine cement produces more ettringite crystals than ordinary cement, forming a certain grid-like structure, thereby enhancing its macro strength.