Experimental Study on Mechanical Properties of Soft Clay Stabilized by Industrial By-Products

The soft clay layers are widely distributed in Southeast China, and the soft clay is of very poor engineering property. The properties of soft clay needs to be improved in advance when the engineering construction projects are carried out. In this paper, mineral powder and fly ash were mixed with cement as the curing agent, and gypsum was used as the activator to stabilize the soft clay. A series of unconfined compressive strength tests and direct shear tests were conducted to investigate the strength of stabilized soil with different ratio. The test results showed that the increase of gypsum content could largely improve the strength of the stabilized soil, while the increase of mineral powder and fly ash did not have a large effect on the strength of stabilized soil. The increase of strength of stabilized soil with curing time was similar to that of cemented soil, and the deformation modulus was about 30.2–119.7 times of unconfined compressive strength. The strength of stabilized soil reached the peak value in this research when the ratio of cement clinker to mineral powder was 6:4, fly ash content was 7.5%, and gypsum content was 20%. The maximum strength of stabilized soil was 994 kPa after being cured for 28 days, which was 2.7 times the strength of cemented soil. There was an obvious linear relationship between unconfined compressive strength and cohesion of stabilized soil, which could be expressed as c = 0.21q_u.