Experimental investigation of crack evolution in expansive soil-rubber mixture (ESR) under freeze-thaw cycles

Abstract

Expansive soil in the seasonally frozen region undergoes a long-term cycle of freezing and thawing. The complex and diverse crack shape that results from repeated swell-shrink distortion of expansive soil poses a serious threat to engineering. Expansive soil-rubber mixture (ESR) improves swelling-shrinkage characteristic and the mechanical properties of expansive soil. Using ESR and expansive soil as test objects, we investigate the effect of rubber powder on the characteristics of expansive soil crack evolution under freeze-thaw cycles. Image processing technologies are used to provide quantitative analysis of the crack images obtained from the test. The results showed that after freeze-thaw cycles, the cracks in the expansive soil specimens had a grid-like and bifurcated pattern with 90° and 120° bifurcations, but the cracks in the ESR specimens had a jagged and dendritic distribution. Comparing ESR and expansive soils, adding 5% rubber powder effectively lowers the complexity of crack evolution and surface crack ratios. The interlocking action of the rubber particles resists the freezing tension on the soil particles, effectively restricting the deformation and opening of the soil particles, decreasing water evaporation and the formation of cracks. In addition, the fractal dimension of ESR and the surface crack ratios satisfy the unique functional relationship under freeze-thaw cycling conditions. Consequently, adding 5% rubber powder to expansive soils might be a realistic and creative strategy for minimizing crack formation in the soil in the seasonal frozen region.