ABSTRACT

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Chapter 4 discussed conventional hydraulic cements used for S/S purposes. Conventional hydraulic cement-based (i.e., grout) S/S processes rely on the chemistry of cement hydration to convert the waste, usually in liquid form, to a solid monolithic product. For some types of waste, e.g., toxic metals, the hydration reaction and associated alkaline pH convert ionic metal contaminants to less-soluble hydroxide forms and thus chemically stabilize the waste. In addition, conversion of the waste into a solid monolithic form, with reduced permeability and surface area in contact with potential groundwater leachant, helps to immobilize both radioactive and hazardous constituents from the environment.