In recent years solidification and stabilization techniques have emerged as viable alternatives for waste disposal. Currently a large number of reputable research organizations and professional companies are engaged in waste stabilization and solidification processes. Unfortunately, stabilization and solidification have been used interchangeably. The fact is that they are two separate processes. Stabilization refers to a chemical technique used to render a waste less toxic or less harmful to the surrounding environment. It reduces the hazard potential of the waste itself. Examples of stabilization techniques include the ion exchange of heavy metals in the alumino-silicate matrix of a cementitious stabilization agent and the sorption of heavy metals on fly ash in aqueous systems. Solidification is used to transform the waste ~as is! into a durable and suitable physical form that is more compatible
for storage, landfill, or reuse. This can be achieved with or
without chemical fixation. It creates barriers between waste components
and the environment by either reducing permeability of
the waste, reducing the effective surface area available for diffusion,
or both.