Micro-Structural Evaluation of Heavy Metal Retention in Stabilization and Solidification with Bentonite and Cement

The main objective of this research is to investigate on the mechanism of cement-clay-heavy metal contaminant interaction at different time intervals from micro-structural point of view. To achieve the above mentioned objective series of buffering capacity measurements, batch equilibrium and XRD experiments were performed on different mixtures of bentonite+contaminant+cement. The results of this study indicate that three process of contaminant retention by clay particles, chemical precipitation, and pozzolanic interaction in solidification process contribute to contaminant retention. Furthermore, the evaluation of XRD analysis indicates that in solidified samples with less than 10% cement, the main reason for reduction in peak intensity of clay fraction is due to the presence of heavy metals. This is attributed to the low pH of lead heavy metal rich electrolyte. However, as the percentage of cement increases, the clay solubility is the main reason for reduction in peak intensity of montmorillonite in XRD test.