The Effects of Portland and Sulphoaluminate Cements Solidification/Stabilization on Semi-Dynamic Leaching of Heavy Metal from Contaminated Sediment

Cement-based solidification/stabilization technology is widely applied in the treatment of heavy metals in river sediment because it is an effective treatment, with the advantages of saving time and being economically and environmentally friendly. In this study, the heavy metal polluted sediment in Shanghai Fuxing Island Canal was used as the raw material, the cement solidified form was prepared by adding 10% Portland cement or sulphoaluminate cement, and semi-dynamic leaching tests were carried out on the solidified forms. In this study, we compare two types of cements as metal conditioners and curing agents aiming to determine the more economical and effective way to utilize river sediments. The results showed that the compressive strength of Portland cement solidified form (PSF) increased with an increase in curing time, which could reach 0.75 MPa after 28 days and met the requirements of general subgrade engineering. The compressive strength of sulphoaluminate cement solidified form (SSF) reached 0.35 MPa after curing for 1 day, however, it decreased later. The semi-dynamic leaching test results showed that the mobility of Cu and Cd in the cement solidified form was low, and the migration mechanism of heavy metals was mainly diffusion. The mobility of heavy metals in the PSF was lower than in the SSF, thus, the PSF had a better solidification effect and was more suitable for treating heavy metal-contaminated sediment.