Tuff-cement or concrete interactions in the repository environment
Hydrothermal interactions of tuff or tuff minerals with cement or concrete were investigated at 200{sup 0}C under a confining pressure of 8 or 30 MPa for 1 to 20 weeks. These chemical interactions produced crystalline hydrous calcium silicates such as Al-substituted tobermorite, xonotlite and gyrolite. Tobermorite was the most common interaction product of cement and tuff or tuff minerals because of pozzolanic reaction. The extent of cement hydration and the quantity of cement in the cement mix affected the abundance of tobermorite as expected. The reaction of concrete with tuff resulted in the formation of smectite in addition to tobermorite due to the generation of slight acidic conditions in this reaction mixture under the present hydrothermal conditions. The formation of tobermorite by the interaction of tuff with cement or concrete has positive implications to the physical (bonding) and chemical (sorption) properties in the repository sealing system because tobermorite (Al-substituted) acts both as a binding agent and as a cation exchanger. 15 refs., 4 figs., 4 tabs.
- Research Organization:
- Du Pont de Nemours (E.I.) and Co., Aiken, SC (United States); New Mexico Univ., Albuquerque, NM (United States); Pennsylvania State Univ., University Park
- OSTI ID:
- 59884
- Report Number(s):
- CONF-841157--; ON: TI85015352; ISBN 0-931837-09-X
- Country of Publication:
- United States
- Language:
- English
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