赤泥复合物固化/稳定化镉污染土特性研究

Characterization of Cd-contaminated soil solidified/stabilized by red mud-based binders

赤泥是工业生产氧化铝产出的固体废渣,产量庞大且具有较强碱性的特点。尝试将赤泥作为碱性激发剂与粉煤灰、粒化高炉矿渣(GGBS)结合用于固化/稳定镉污染土,对养护7、14、28 d试样的无侧限抗压强度特性、剪切特性、重金属浸出特性和微观结构进行研究。研究结果表明:土中镉离子会降低土体强度,掺入赤泥、GGBS和粉煤灰后土体强度相应增强;镉离子初始浓度会对赤泥基固化土强度造成影响,当初始值高于临界浓度值,土体强度开始逐渐降低;土中镉浓度的增加会降低土体剪切强度和黏聚力,同时增大摩擦角;赤泥-GGBS固化土有较高的强度和较低的重金属浸出率,相较于赤泥-粉煤灰有更好的固化/稳定效果。

Red mud is a solid waste residue from the production of alumina,which is highly alkaline and produced with huge amount.In this study,red mud was used as an alkaline activator combined with fly ash and ground granulated blast-furnace slag(GGBS)to solidify/stabilize cadmium contaminated soil.The unconfined compressive strength,shear characteristics,heavy metal leachability and microstructure of the samples cured for 7,14 and 28 days were studied.The results show that:Cadmium ions in soil reduce the strength of soil,and the strength of soil increases after the addition of red mud,GGBS and fly ash;the initial concentration of cadmium ions affects the strength of red mud-based solidified soil.When the initial value is higher than the critical concentration value,the soil strength begins to decrease gradually;the increase of cadmium concentration in soil reduces the shear strength and cohesion of soil and increase the friction angle.Compared to red mud-fly ash,red mud-GGBS has higher unconfined compressive strength and lower heavy metal leaching concentration.