Effect of dry-wet cycle on dynamic mechanical characteristics of EPS cement soil under different chloride salt environments

Abstract

As a new type of lightweight filling material, EPS (Expanded polystyrene) cement soil often faces the effects of chloride erosion and dry-wet cycles in engineering. Therefore, based on the Hopkinson pressure bar test, this study analyzes the dynamic mechanical properties of EPS cement soil specimens with different dry-wet cycles under different chloride environments. The main conclusions are as follows: Under the action of impact load, the stress-strain curve of EPS cement soil specimen is roughly divided into three stages, elastic deformation stage, strengthening stage and failure stage; the regression analysis of the results of dynamic compressive strength was carried out, and the expression of dynamic compressive strength with the concentration of sodium chloride solution and the number of dry-wet cycles was obtained. The correlation coefficient R2 > 0.98. The regression analysis of absorption energy and energy absorption efficiency was carried out respectively. It was found that after 15 dry-wet cycles in 30 g / L sodium chloride solution, the absorption energy and energy absorption efficiency reached the lowest, which were 15.19 J and 23.26 % respectively, which were 36.52 % and 34.28 % lower than those without dry-wet cycles. The impact toughness index of cement soil specimens decreases with the increase of the unmber of dry-wet cycle and sodium chloride solution concentration. Finally, the mechanism of strength change of cement soil specimens was analyzed from the microscopic point of view combined with SEM images.