FeSO_(4)-GFC胶凝材料固化/稳定Cr(Ⅵ)污染土的工程结构理化特性

Engineering structure and physicochemical properties of Cr(Ⅵ)contaminated soils stabilized/solidified by FeSO_(4)-GFC

为研究固化/稳定后Cr(Ⅵ)污染土的工程结构理化特性,以硫酸亚铁(FeSO_(4))和碱性工业废渣胶凝材料(简称GFC)固化/稳定后Cr(Ⅵ)污染土为试验对象,分别剖析了药剂组分、养护时间对FeSO_(4)-GFC胶凝材料固化/稳定Cr(Ⅵ)污染土的工程结构理化特性的影响规律.结果表明:提高GFC的掺量和养护龄期可快速增加修复土的pH、最大干密度、液限、典型粒径,提高修复土的物理性质;但提高GFC的掺量和养护龄期会造成修复土氧化还原电位增大,弱化了Cr(Ⅵ)的还原效果,增加环境风险,FeSO_(4)-GFC会显著改变修复后Cr(Ⅵ)污染土的工程结构,引起比表面积和平均孔径变小.GFC生成的C-A-S-H、C-S-H和AFt等物质,会造成污染土颗粒出现团聚现象,改变了修复后粒径分布、孔隙结构和物质组成,这是FeSO_(4)-GFC固化/稳定后的Cr(Ⅵ)污染土理化性质改变的内在原因.

In order to study the engineering structure and physicochemical properties of Cr(Ⅵ)contaminated soils stabilized/solidified by FeSO_(4)-GFC,the effect of GFC-FeSO_(4) ratio and curing age on engineering structure and physicochemical properties were investigated in this paper.Results show that the pH,maximum dry density,liquid limit and typical particle size and physicochemical properties increased positively with the GFC-FeSO_(4) ratio and curing age.However,the redox potential also increased,resulting in reduced Cr(Ⅵ)reduction rate and increased environmenta.The engineering structure of Cr(Ⅵ)contaminated soils treated by GFC-FeSO_(4) was significant changed with decreased average pore size and specific surface area.The mechanism of physicochemical property change on GFC-FeSO_(4) stabilized/solidified Cr(Ⅵ)contaminated soils was the formed precipitate such as AFt,C-S-H and C-A-S-H which caused soil aggregates and changed the size distribution,pore structure and material composition.