Authors: Yang Li Xingbao Gao Qi Wang Jie He Dahai Yan
Publish Date: 2014/12/04
Volume: 22, Issue: 9, Pages: 6877-6885
Abstract
Fly ash FA for reuse as a construction material is activated using two methods to produce hydrated silicate and geopolymer gels We investigated the solidification/stabilization and leaching behavior of PbCl2 in a geopolymer matrix GM and hydrated silicate matrix HSM based on FA as the source material to evaluate the environmental and health risks The GM and HSM synthetic conditions were 60 °C 20 relative humidity RH and 12 wt 6 mol/L NaOH and 20 ± 2 °C ≥90 RH and 30 wt respectively based on their compressive strength performances Xray diffraction XRD showed that Pb participated in hydration and geopolymerization and was incorporated in the structural components of the hydrated silicate and geopolymer In leaching experiments the solidification/stabilization effects of Pb and Cl in the HSM and GM improved with increasing curing time After longterm curing 28 days the immobility of Pb in the GM was better than that in the HSM Sodalite improved the Clstabilizing ability of the GM compared with that of the HSM In static monolithic leaching experiments HSM and GM had the same Pbleaching behaviors Based on the changes in the location of the neutral sphere layer with decreasing acidneutralizing capacity Pb release was divided into alkalinerelease stagnation and acidrelease stages The neutral sphere layer contained the highest Pb concentration during permeation toward the block center from the block edge This behavior regulation could also apply to other amphoteric metals immobilized by GMs and HSMs
Keywords: