Abstract: A method of incorporating a material in a settable binder is disclosed. The binder includes a source of caustic magnesium oxide. The method involves mixing the material with the binder, either as part of a slurry or for subsequent formation into a slurry, and then adding a setting agent to the slurry. The setting agent is added to enhance setting of the binder. The material can be a hazardous waste material or components thereof. The inventors have surprisingly discovered that when the setting agent is added after mixing of the material with the binder, that a superior setting of the material in the binder can be achieved. The settable composition can comprise only a caustic magnesium oxide binder and a setting agent for the binder, as the inventors have surprisingly discovered that there is no need for any other binding agents, thus providing a simpler binder composition and method of use.

Abstract: A method of encapsulating hazardous waste materials including heavy metals such as arsenic, mercury, nickel and chromium residues, as well as radioactive materials. The method involves adding the hazardous waste material to a settable composition, forming a slurry, and allowing the slurry to set to encapsulate the waste material. The settable composition is a powdered flowable cement composition containing calcium carbonate and a caustic magnesium oxide. Tests conducted on the encapsulated material indicate that virtually none of the hazardous waste material is leached out of the set composition which has a concrete-like appearance.