Abstract: The invention provides a method for the production of a stable monolith, the method comprising the encapsulation of a waste material in the monolith by means of chemical bond formation within the monolith, and a method for the disposal and storage of waste materials, which comprises the production of a stable monolith by such method. Waste materials which are particularly suited to treatment according to the invention include various geopolymer precursors, most particularly ion exchange materials such as aluminosilicate materials, and the invention is particularly suited to the disposal and long term storage of radioactive waste materials.

Abstract: The invention provides a method for the encapsulation of fine particulate materials which comprises treating these materials with a microfine hydraulic inorganic filler which, typically, comprises a cementitious material, such as Portland Cement. The filler is ground to a much smaller particle size than is normally used in the production of a grout and is provided in the form of an aqueous composition for the treatment of the fine particulate materials by pumping under pressure through these materials such that they become intimately encapsulated. The method is particularly applicable to the treatment of waste materials and, most particularly, waste materials which are encountered in the nuclear industry.

Abstract: The invention provides a cementitious composition comprising at least one sulphoaluminate cement which comprises a sulphoaluminate salt of an alkaline earth metal, the cementitious composition being essentially free of other cementitious components. Preferably the at least one sulphoaluminate salt of an alkaline earth metal comprises calcium sulphoaluminate and the cementitious composition additionally comprises at least one further salt of an alkaline earth metal, preferably calcium sulphate. The invention also provides a method for the encapsulation of materials, the method comprising treating the materials with the said at least one cementitious composition. Preferably, the materials which are encapsulated according to the method of the invention comprise waste materials generated in the nuclear processing industry comprising amphoteric reactive metals.