Disintegration behaviors of red clay under wet-dry cycles

Abstract

Cyclic wetting-drying alternation has a significant influence on the strength and structure of soils. It is prone to causing soil softening and disintegration, highlighting the importance to improve the soil's resistance to disintegration. This paper utilizes a self-developed disintegration test apparatus to analyze the disintegration characteristics of improved red soil under wet-dry cycles, focusing on the disintegration amount and ratio. Furthermore, XRD (X-ray diffraction), SEM (scanning electron microscope), tensile test, and contact angle test are employed to investigate the anti-disintegration behaviors of the improved red soil. The results show that the disintegrating amount and ratio of undisturbed and improved red soil are distinctly different under wet-dry cycles. Linear, stepped, constant and concave but perfect "S" shapes of the disintegrating ratio are observed in the cyclic tests. Cement and lime strengthen the red soil primarily through hydration reaction. The drop experiment confirms that cement plays a crucial role in restraining the disintegration. When the ameliorant content is low, the correlation between pore parameters and disintegration duration of red soil follows the order: mean shape coefficient > fractal dimension > probability entropy > area probability distribution index. With a high ameliorant content, the correlation remains similar, with slightly higher correlation for probability entropy. Under wet-dry cycle conditions, sludge and kaolin can improve the soil through the bonding of clay particles. The improved water repellency greatly enhances the resistance to disintegration of the altered red soil. The research provides valuable insights for the practical application of soil.