Study on the crack behavior of expansive soil modified with crushed oyster shell under dry-wet cycles

Purpose This study aims to investigate the shear strength and cracking behaviour of crushed oyster shell (COS) modified expansive soil following dry-wet cycles and to determine the optimal COS content. The study analyses the impact of COS on the properties of expansive soil. Design/methodology/approach The crack development characteristics of COS modified soil were quantitatively analysed using a combination of direct shear tests, microscopic experiments and the Particles and Cracks Analysis System (PCAS). Findings COS can effectively enhance the soil particle distribution, increase the internal friction angle and bolster the shear strength of the soil. The bonding and agglomeration effects are crucial for strengthening expansive soil and controlling crack formation. To minimize cracking in the modified soil after multiple dry-wet cycles, it is recommended that the COS content be maintained at 9%. Originality/value The study employed PCAS software to quantify the soil’s crack rate and utilized SEM image to analyse the crack generation patterns in the modified soil. This research provides a scientific foundation for the application of COS modified expansive soil.