Mineralogical alterations that affect the durability and metals containment of aged solidified and stabilized wastes

Detailed research on the weathering and degradation of solidified and stabilized wastes once treated materials have been buried is lacking, and published data to verify the long-term performance and durability of landfilled treated wastes over time are still only limited. Optical and electron microscopy techniques were used in this study to evaluate features associated with metal-bearing contaminated soil and industrial wastes that have been solidified and stabilized with Portland cement and stored outdoors, archived in the laboratory, or buried on site. Results show that although the extent of degradation after 6 years is considered slight to moderate, the same environmental factors that affect the durability of concrete also must be considered when evaluating the durability and permanence of cement-stabilized and solidified wastes. Furthermore, evaluations of durability and permanence cannot be based on leaching and chemistry analyses alone. The use of all levels of microscopic analyses are needed to accurately evaluate the long-term performance of solidification/stabilization technologies. In addition, regulations for the on-site burial of treated wastes, even after they are rendered nonhazardous, are needed. Burial of cement-based solidified and stabilized wastes in deleterious environmental zones, such as acid or saline soil, as well as fluctuating groundwater systems is not recommended.

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