Abstract: In this paper, the effect of cyclic freezing and thawing on the physical and mechanical properties of expansive soil improved by microwave heating is studied. The industrial microwave oven is used to heat the expansive soil at high temperature for different times to improve the original expansive soil. The volume deformation, compressive strength, X-ray diffraction (XRD) and microstructure tests were carried out on the samples after 0, 1, 3, 6 and 10 cycles of freeze-thaw. The results showed that under the optimum moisture content, the soil samples at different microwave times show "freeze shrinkage and thaw expansion" during the cyclic freeze-thaw process. The unconfined compressive strength and elastic modulus of expansive soil after microwave heating under freeze-thaw cycles decrease with the increase of freeze-thaw cycles, especially at the beginning stage. Under the same freezing and thawing times, the strength and elastic modulus of the improved expansive soil by microwave heating increase with the increase of microwave time, and the microwave effect effectively reduces the freezing and thawing damage. The effect of freeze-thaw cycles on micro-pore area of microwave modified expansive soil is as follows: the more freeze-thaw cycles, the higher the proportion of large pore area, and the lower that of small pore area. It shows that the freeze-thaw cycles have a great impact on the soil structure.
Keywords: freeze-thaw cycle; microwave heating; expansive soil; MATLAB software; microscopic characteristics
合肥工业大学学报自科版