Investigating static properties and microscopic pore structure characteristics of rubberized cement-soil under freeze-thaw cycles

Subgrade soil undergoes freezing in winter and thawing in summer in seasonal frost areas, which severely impacts the engineering performance of the subgrade soil. In order to enhance the frost resistance of subgrade while mitigating the environmental impact of incinerating industrial solid waste, rubber crumb was added to cementsoil in this study. The static triaxial and mercury intrusion porosimetry tests were conducted on freeze-thawed cement-soil and rubberized cement-soil. The effects of the number of freeze-thaw cycle and confining pressure on peak strength and initial elastic modulus were investigated. The pore size distribution, porosity, and fractal dimension under various numbers of freeze-thaw cycle were obtained based on the MIP test results. The damage parameter of the specimens was determined using the fractal dimension. A constitutive model with damage parameter of rubberized cement-soil was established. The results showed that the pore size distribution of the specimens deteriorated after the whole freeze-thaw cycles, with increases observed in macropore proportion, porosity, and damage parameters, while peak strength and fractal dimension decreased. The macropore proportion of cement-soil and rubberized cement-soil increased by 14.9% and 2.0%, respectively. The incorporation of rubber particles suppressed the development of pores and cracks and enhanced the frost resistance of the specimens. The damage parameter of rubberized cement-soil decreased by only 0.0186 by the end of 12 of freezethaw cycle. The established constitutive model was suitable for characterizing the stress-strain behavior of rubberized cement-soil. The findings facilitate the construction and design of subgrade engineering in seasonal frost areas, contributing to the development of sustainable, durable subgrade solutions and reducing the environmental impact of waste rubber tires.