Rice husk ash (RHA) as cement admixture for immobilization of liquid radioactive waste at different temperatures

Abstract

Cementitious materials will initially act as a mechanical barrier preventing activated water flow through the waste for a long time, and thus will contribute to the retardation of dissolved radionuclides by the combination of physical and chemical interactions. Most chemical species in aqueous solutions will undergo some kind of (chemical) interactions with any solids of the cementations material. Therefore, it is of great importance to develop a quantitative understanding of the chemical processes involved and to strictly differentiate between physical and chemical aspects of radionuclide transport through such materials. A study is undertaken to determine the waste immobilization performance of (Cs +) wastes in cement–RHA mixtures. In addition to evaluating the effects of RHA on the leaching properties of cemented waste forms, the effect of addition of (RHA) on the strength of the cemented waste form is also investigated. However, RHA addition of 30% causes a significant increase in the hydraulic stability of cemented waste form. RHA enhances the strength; leaching and durability of cement may be through three primary actions which are the filler effect, the acceleration of ordinary Portland cement hydration and the pozzolanic reaction with calcium hydroxide (CH). The results were compared to control sample, and the viability of the RHA addition to concrete was verified. The use of these minerals results in ecological, economic and energy saving considerations.