磷酸镁水泥固化铜污染土的工程特性

为研究不同水泥固化重金属污染土的处理效果和工程特性,取掺重金属铜的高岭土作为研究对象,考虑磷酸镁水泥(magnesium phosphate cement,MPC)掺量、养护龄期、初始铜离子浓度三种因素,研究了MPC固化后重金属铜污染土的固化效果及特性.基于无侧限抗压强度试验和扫描电镜试验,分析了三种因素对固化铜污染土的强度和微观结构的影响,并得到固化土抗压强度与内部孔隙所占百分比之间的关系.无侧限强度试验结果表明,MPC固化铜污染土的效果显著;随着MPC掺量的增多和养护龄期的增长,固化土的抗压强度增大;随着初始铜离子浓度的增大,固化土的抗压强度减小,且当污染土中铜离子浓度过高时,固化效果降低.微观试验结果表明,固化过程中既有物理包覆又有化学反应,随着MPC掺量的增多、养护龄期的增长,固化土的孔隙百分比降低,结构变得更加致密,随着初始铜离子浓度的增大,孔隙所占百分比增大,土体结构变得疏松,固化土体强度降低.

Research on Engineering Characteristics of Magnesium Phosphate Cement Solidified Copper Contaminated Soil

In order to study the treatment effect and engineering characteristics of different cement-solidified heavy metal contaminated soils, kaolin doped with Cu2+ was taken as the research object, considering the three factors of magnesium phosphate cement (MPC) dosage, curing age and initial copper ion concentration, MPC curing was studied solidification effect and characteristics of post-heavy metal copper contaminated soil. Based on the unconfined compressive strength test and the scanning electron microscope test, the effects of three factors on the strength and microstructure of the solidified copper contaminated soil were analyzed, and the relationship between the compressive strength of the solidified soil and the percentage of internal pores was obtained. The unconfined strength test results show that the effect of MPC on solidifying copper contaminated soil is significant; with the increase of MPC content and the growth of curing age, the compressive strength of solidified soil increases; as the initial copper ion concentration increases, the compressive strength of the solidified soil decreases, and when the concentration of copper ions in the contaminated soil is too high, the solidification effect decreases. The microscopic test results show that there are both physical coating and chemical reaction during the curing process. As the MPC content increases and the curing age increases, the percentage of pores in the cured soil decreases and the structure becomes denser. As the initial copper ion concentration increases, the percentage of pores increases, the soil structure becomes loose, and the strength of the solidified soil decreases.