Dissolution-precipitation behaviour of ettringite, monosulfate, and calcium silicate hydrate
The stability of the cement minerals ettringite, monosulfate, and calcium silicate hydrate (C-S-H) was investigated to better understand the uptake of contaminants in waste-cement mixes. Suspensions were spiked with radioisotopes of components ({sup 45}Ca and {sup 35}SO{sub 4} for ettringite and monosulfate and {sup 45}Ca and {sup 32}Si for C-S-H) to observe their uptake behaviour within 0-70 days. A physical model was applied to determine dissolution-precipitation rates. An initial fast uptake was observed to occur in most systems, so the data obtained between 7 and 70 days were chosen for analysis. Dissolution-precipitation rates were in the range of 10{sup -11.5} to 10{sup -12.2} mol m{sup -2} s{sup -1} for all minerals. The whole solids would be dissolved and reprecipitated within 1-4 years. The measured dissolution-precipitation rates of pure cement minerals give the maximum rate for ion substitution processes with contaminants and are distinguishable from faster processes such as surface complexation and ion exchange processes.
- OSTI ID:
- 20658341
- Journal Information:
- Cement and Concrete Research, Vol. 34, Issue 2; Other Information: DOI: 10.1016/j.cemconres.2003.08.016; PII: S0008884603002941; Copyright (c) 2003 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0008-8846
- Country of Publication:
- United States
- Language:
- English
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