Deterioration mechanism of mechanical properties and microstructure in xanthan gum-reinforced soil under wetting-drying cycles based on CT scanning technology

The wetting-drying cycle has an important effect on the engineering properties of rock and soil. The CT scanning technology and testing methods for mechanical properties are used to study the deterioration mechanism of clay reinforced with xanthan gum with different contents (0%, 0.5%, and 1.5%) under different times of wetting-drying cycles (0, 1, 4, 8, 12). The main conclusions are as follows: (1) The xanthan gum can effectively improve the compressive strength and wetting-drying resistance of the soil. With the increase of the xanthan gum content, the strength loss after wetting-drying cycles decreases gradually. When the times of cycles increase from 0 to 4, the compressive strength of the soil with the xanthan gum contents of 0%, 0.5% and 1.5% decreases by 42.75%, 17.2% and 14.04%, respectively. (2) There is an exponentially decreasing relationship between the compressive strength of the reinforced soil and the times of wetting-drying cycles. When the times of cycles reach 4, the change values of the compressive strength and the elastic modulus of the samples all fluctuate in a small range with the further increase of the times of cycles. (3) With the increase of the times of wetting-drying cycles, the porosity of the xanthan gum-reinforced soil shows a trend of increasing first and then decreasing. With the increase of the times of the wetting-drying cycles, the connected pores continue to expand, while the isolated pores show a trend of increasing first and then decreasing. (4) With the drying of the sample, the xanthan gum forms a network matrix among the soil particles, which improves the strength of the soil and the capability of resistance to wetting-drying cycles.