Effects of curing age and initial water content on the properties of solidified chromium-contaminated shield muck

A cement-quicklime composite curing agent was developed for solidifying chromium-contaminated shield muck to overcome the problems of high emissions and unsatisfactory curing performance of single curing materials and to realize resource utilization. The ratio of the composite curing agent was determined by single material curing tests and orthogonal tests, and the impact of curing age and initial water content on the curing performance was discussed. When the cement content is greater than 5 %, the solidified soil strength increases significantly. The addition amount of quicklime has a critical value of 4 %. The strength of test No 13 solidified soil with a curing age of 14 days reaches 1217.58 kPa, and the leaching toxicity is 2.4 mg/L, which meets the requirements of relevant specifications; the unconfined compressive strength of the solidified soil is closely related to the leaching toxicity, as shown by the fact that the greater the unconfined compressive strength is, the less leaching toxicity there is. The relationship between the unconfined compressive strength and curing age is a power function of y = 1289.4(x - 13.3)(0.17) (R-2 = 0.992), and the solidified soil has greater strength when the initial water content of the shield muck is close to the liquid limit (34.43 %).