Experimental study of zn and pb contaminated soils stabilized with new phosphate-based binder under freeze-thaw cycles

A novel phosphate-based binder(KMP) and Portland cement(PC) are used to stabilize the contaminated soils spiked with Zn and Pb. The strength and durable characteristics are evaluated by toxic characteristics leaching procedure(TCLP) tests, unconfined compressive strength(UCT) and sequential extraction procedures(BCR) after freeze-thaw cycle. The TCLP result shows that the leaching Zn and Pb value exceed the limit of china MEP regulatory but up to the stander after solidified by KMP and PC binder in the untreated soil. The UCT result shows that solidified soil is lower than the stander curing soil treated by freeze-thaw cycle. After 12 freeze-thaw cycles the qu of heavy metal contaminate soil solidified by KMP is higher than the PC. The MIP result shows that the pore size increases with the increase of freeze-thaw cycles. The BCR result shows that the exchangeable fraction Zn and Pb reduce with the increase of curing time but the residual fraction increases which soil solidified by KMP and PC.