title: Stabilization/solidification of hazardous and radioactive wastes with alkali-activated cements.
abstract: This paper reviews progresses on the use of alkali-activated cements for stabilization/solidification of hazardous and radioactive wastes. Alkali-activated cements consist of an alkaline activator and cementing components, such as blast furnace slag, coal fly ash, phosphorus slag, steel slag, metakaolin, etc., or a combination of two or more of them. Properly designed alkali-activated cements can exhibit both higher early and later strengths than conventional portland cement. The main hydration product of alkali-activated cements is calcium silicate hydrate (CSH) with low Ca/Si ratios or aluminosilicate gel at room temperature; CSH, tobmorite, xonotlite and/or zeolites under hydrothermal condition, no metastable crystalline compounds such as Ca(OH)(2) and calcium sulphoaluminates exist. Alkali-activated cements also exhibit excellent resistance to corrosive environments. The leachability of contaminants from alkali-activated cement stabilized hazardous and radioactive wastes is lower than that from hardened portland cement stabilized wastes. From all these aspects, it is concluded that alkali-activated cements are better matrix for solidification/stabilization of hazardous and radioactive wastes than Portland cement.
authors.affiliation: School of Civil Engineering and Architecture, Central South University, Changsha, China. cshi@cjs-technology.com
authors.forename: Caijun
authors.initials: C
authors.lastname: Shi
authors.forename: A
authors.initials: A
authors.lastname: Fernández-Jiménez
mesh_terms: D000468:Alkalies / Q000737:chemistry*; D003252:Construction Materials; D015386:Hazardous Substances; D011850:Radioactive Waste; D018505:Waste Management / Q000379:methods*; D014875:Water Pollutants, Radioactive / Q000737:chemistry*
chemical_list: D000468:Alkalies; D015386:Hazardous Substances; D011850:Radioactive Waste; D014875:Water Pollutants, Radioactive