Alteration Behaviors of Granite Minerals Forming Calcium Silicate Hydrate under Ca-Rich Highly Alkaline Conditions - 16160
- Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, 6-6-01-2, Aramaki, Aza-Aoba, Aoba-ku, Sendai 980-8579 (Japan)
Cementitious materials used for geological disposal systems leach large amounts of alkaline ions (Ca{sup 2+}, Na{sup +}, K{sup +}) into groundwater, and alter the pH of groundwater by up to 13. The altered groundwater contacts the host rock and forms Calcium Silicate-Hydrate (CSH) through the interaction of Ca ions and the silicate species, which in turn clogs the flow paths of the host rock. This clogging effect in the flow paths is expected to retard the migration of radionuclides. A previous study reported the heterogeneous formation of CSH on the surface of granite under Carich and highly alkaline conditions. To clarify the formation process of CSH, this study examined the CSH formation with the dissolution of some minerals contained in the granite under Ca-rich and highly alkaline conditions. In the experiments, the granite block and the crushed minerals contained in the granite were immersed in a 6.4-8.5 mM Ca(OH){sub 2} solution adjusted pH to 12.5 by adding NaOH solution. As a result, biotite and anorthite supplied more Si to the formation of CSH than other minerals. Furthermore, most of the formed CSH precipitated on the solid surface although a little CSH remained in liquid phase as supernatant. These results suggest that under Ca-rich highly alkaline conditions the CSH formed as a secondary mineral will retard the migration of radionuclides released from the repository because of the clogging effect of the flow path. (authors)
- Research Organization:
- WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
- OSTI ID:
- 22838042
- Report Number(s):
- INIS-US-19-WM-16160; TRN: US19V1235083397
- Resource Relation:
- Conference: WM2016: 42. Annual Waste Management Symposium, Phoenix, AZ (United States), 6-10 Mar 2016; Other Information: Country of input: France; 8 refs.; available online at: http://archive.wmsym.org/2016/index.html
- Country of Publication:
- United States
- Language:
- English
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