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|Title:||Studies of the geochemical stability of a salt-saturated expansive grout|
|Authors:||Sandia National Laboratories.|
Wakeley, Lillian D.
Poole, Toy S.
Radioactive waste disposal
Waste Isolation Pilot Plant
|Publisher:||Structures Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; SL-87-10.|
Abstract: This report describes laboratory experiments on several aspects of durability of grout in the special environment of a repository for radioactive wastes in bedded halite rock. The variables tested include solubility of grout components, phase changes, and mobility of chloride relative to interfaces with rock and brine or freshwater. The grout tested had large percentages of both chloride and sulfate. Chloride was more mobile when the grout was exposed to freshwater, and sulfate when exposed to brine. Removal of chloride from the grout accompanied loss of chloroaluminate phase, rather than simply dissolution of NaCl. However, chloride gradients were not apparently related to an interface between grout and halite rock. With extended exposure to brine or freshwater, calcium represented the largest fraction of mass loss, as determined by analyses of exposure solutions. Sulfate loss was the second largest. This effect increased with time and temperature of exposure. Volume increase of test specimens indicated continued or renewed expansion, even after the initial curing or storage period (28 days or 9 months), when the grout was exposed to water or brine. The combination of volume increase with mass loss suggests a density decrease, but this did not cause loss of physical integrity of specimens. Analyses of phase compositions and changes will be reported in a subsequent document.
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