水泥固化锌污染红粘土力学特性及强度预测

Mechanical Property and Strength Prediction of Cement-Solidified/Stabilized Zinc-contaminated Red Clay

将重金属污染土与水泥混合固化处理后,可防止重金属向周围进一步扩散,并可作为稳定的固化材料用于浅层地基等非敏感区域,达到污染土二次利用的目的。将人工制备的锌污染红粘土通过水泥固化处理后,进行无侧限抗压强度试验,研究不同水泥掺量、污染物浓度和养护龄期下固化物的无侧限压缩变形特性。研究结果表明:锌离子浓度对水泥固化土的强度和变形模量存在阈值,且随着水泥掺量的增加,浓度阈值增加。锌离子浓度在5000mg·kg-1以内,固化土的应力-应变曲线经历弹性变形阶段、弹塑性变形阶段、破坏阶段和残余强度阶段,且水泥掺量大于8%时,破坏应变随龄期增加而增大。锌离子浓度在10000 mg·kg-1时,固化物的弹性变形阶段经历短暂后直接进入残余强度阶段。固化物的变形模量随着锌离子的增加而减小,但当水泥掺量10%时,少量的锌离子会提高固化产物的变形模量。通过对不同水泥掺量、养护龄期和污染物浓度的固化物强度进行拟合分析,最终得到了与试验结果吻合度较高的水泥固化锌污染红粘土强度预测经验公式。

The solidification process of the heavy metal pollution of soil and cement can prevent heavy metal from further spread to the surrounding as well as be treated as a building material stable curable material used in non-sensitive areas such as shallow foundation in order to use the polluted soil for a second time. Unconfined compression tests were carried out after the curing treatment of zinccontaminated red clay cement prepared by humans. The aim was to study different cement content, the concentration of pollutants and deformation characteristics of limitless compression of condensate under curing period. The results show that there exists a threshold of strength and deformation modulus of cement stabilized soil which is related to zinc ion concentration, and the concentration threshold increases with the increase of cement content. When zinc ion concentration is less than 5000 mg · kg-1, stabilized soil stress-strain curves undergo elastic deformation stage, the stage of plastic deformation as well as damage and residual strength stage phase. What＇s more, if cement introduction rate is more than 8%, the failure strain is positively correlated with age. On the other hand, when zinc ion concentration is 10000 mg· kg-1, the condensate directly steps into the residual strength stage after a short curing elastic deformation stage. The deformation modulus of condensate decreases with the increasing of zinc ions , but when the cement content is 10%, a small amount of zinc ions will increase the deformation modulus of the cured product. Through the fitting analysis on different cement content, curing age and pollutant concentrations, the author eventually gets the empirical formula predicting the intensity of the red clay which highly agrees with the experimental results of a higher degree of cementation zinc pollution.