Abstract:

New type magnesium phosphate cement（MPC） was used to solidificate volatile heavy metal Zn.By measuring the compressive strength,leaching rate of Zn ²⁺ and composition of hydration products,the surface microstructure of solidified ce-ment was observed and the occurrence and chemical states of heavy metal Zn in MPC were analyzed.Then, the solidification effect and mechanism of new type MPC on heavy metal Zn were explored.Results showed that when the doping content（mass fraction） of Zn ²⁺ increased from 0 to 4%,the compressive strength at 56 d decreased by 21.9%.When the doping content of Zn ²⁺ was 4%,the maximum leaching mass concentration reached 6.6 mg/L at 1 d.Zn ²⁺adversely affected the hydration process.The Solidification effects of MPC on Zn included physical coating and chemical binding.Zn existed mainly in form of Zn₂（PO₄）（OH）,and solidified Zn ²⁺ didn′t change by MPC.

Key words: MPC, heavy metal Zn, solidification mechanism