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Cementitious Mixtures for Sealing Access Shafts/Boreholes Through Evaporite and Clastic Rocks in a Radioactive-Waste Repository
Published online by Cambridge University Press: 26 February 2011
Abstract
Geochemically compatible cement-based mixtures were designed for sealing a potential geologic repository for high-level radioactive waste in evaporite and related rock strata. The slightly expansive cementitious mixtures were based on Class H cement and Class C fly ash, with silica and calcium sulfate additives, and a low ratio of water to cementitious solids (w/s = 0.32). Both a salt-free and a salt-containing version were used in tests with anhydrite/siltstone and halite.
Although it is difficult to achieve strong bonding between anhydrite and cement-based mixtures, tensile bond strengths, interface permeability, and other properties of the composites as a whole indicate achievement of the desired chemical and physical compatibility between these materials Integrity of bonding and low permeability to water (on the order of 110 darcy) suggest the likelihood of attaining durable sealing of repository access shafts/boreholes through the use of such chemically tailored cementitious mixtures.
Rock samples used in ongoing sealing studies were obtained from various areas throughout the United States. The data in the present paper represent results for rocks obtained from the Palo Duro Basin and as such typify bedded-salt strata.
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- Copyright © Materials Research Society 1985
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