Effect of additives on the bituminization of hazardous wastes

Abstract

Cement and bitumen have been used as solidification agents for the radioactive waste from the early stage of nuclear industry, 1960``s. Bituminization is developed for the purpose of improving characteristics of cementation, such as the very low leach resistance and the volume increment. Bituminization can get the volume reduction factor of 1.5 ~ 6 and bituminized waste forms have a high leach resistance, however the mechanical stability is unacceptable. For industrial hazardous wastes, the portland cement has been the most common solidification agent since 1980``s. In Korea, these wastes are solidified with cement in Hwasong and Onsan. After being cured in the mold for several days at room temperature, cemented waste forms is removed from the mold and disposed in the landfill without any packaging. If the bituminized waste forms can hold the mechanical and dimensional stability; i) It is economical because the waste form itself without extra packaging can be disposed as cemented waste forms does. ii) The long-term stability of waste form at landfills can be guaranteed. iii) It is possible to evaluate the bituminized waste forms exactly. The precise leach test can not be performed for bituminized waste forms which have no mechanical stability due to the deformation during the test. The objectives of this thesis are; i) to develop bituminized waste forms which can keep their own merits together with mechanical and dimensional stability like cement-based waste forms, and ii) to evaluate bituminization conditions for hazardous wastes and leaching mechanism of heavy metals from bituminized waste forms. The bitumen used in sample preparation is straight-run distillation bitumen of penetration 60/70. Bottom ash from a hazardous waste incinerator and plating sludge from an industrial plating factory were chosen as hazardous wastes. Summarized conclusions for each topic are as follows; Regarding the effect of additives on the mechanical stability: Maximum loading of as...