Effects of Snow-Melting Salt on Mechanical Properties of Low-Exothermic Polymer Grouting Materials

Low-exothermic polymer grouting materials are classified as early-strength repair materials, and are used widely in road repair in seasonal frozen regions. Roads in these regions frequently are affected by snow-melting salt. Snow-melting salt can directly affect the mechanical properties and durability of road materials. In this study, salt-immersion (S-I) and salt–freeze–thaw (S-F-T) cycles were used to study the effects of snow-melting salts on low-exothermic polymer grouting materials with different densities. Subsequently, tests for water absorption, uniaxial compression, uniaxial tension, and scanning electron microscopy were carried out to study the changes in water absorption, mass, compressive strength and tensile strength of the materials under different immersion times and different numbers of S-F-T cycles. Ultimately, the mechanism of material mass loss and strength loss was determined from a microscopic perspective. The results indicate that during the S-I process, the water absorption of materials in salt solution is lower than that in water. However, the S-I process has minimal impact on the mechanical properties of the materials. The S-F-T cycles process exhibits a more pronounced detrimental effect on the materials, which originates from the breakage and deformation in their cell structure. As the number of S-F-T cycles increases, the cell structure of the materials gradually is damaged, leading to an initial increase in water absorption followed by a stabilization trend. Following immersion in liquid, the freeze–thaw damage is exacerbated further, resulting in a reduction of mass, compressive strength, and tensile strength of the materials. During the S-F-T process, the mass loss rate of the materials in CaCl2 solution was the highest, approximately 1.4 times that in CH3COOK solution and 2 times that in water. Simultaneously, the compressive strength loss rate of materials after 200 S-F-T cycles was the highest in CaCl2 solution, followed by CH3COOK solution, and it was lowest in water. Furthermore, materials with higher density had lower loss rates in terms of compressive strength, tensile strength, and mass, indicating enhanced resistance to freeze–thaw damage. The research findings provide a crucial basis for evaluating the application and durability of low-exothermic polymer grouting materials in seasonal frozen regions.