Estimating Geochemical Behavior of Cocnretes to be Placed at Yucca Mountain

by Thomas E. Hinkebein, Sandia Natl Lab, Albuquerque, United States,
Mark A. Gardiner, Sandia Natl Lab, Albuquerque, United States,

Document Type: Proceeding Paper

Part of: High Level Radioactive Waste Management 1991


The interactions of J-13 water with cementitious materials were examined at 25°C using the geochemical code EQ3NR/EQ6. Results of the modeling suggested the following conclusions: (1) Solution chemistry for calcium-rich concretes was similar to that for silica-rich concretes. (2) Solution pH was strongly buffered by J-13 water at neutral values for small amounts of added concrete. For larger amounts of concrete the pH was dominated by the concrete and typically had values near 12. (3) If ettringite or excess portlandite are present, their decomposition opens the concrete structure. Excess silica reacts with hydrogarnet to tighten the concrete structure. (4) The permeability changes for the limited conditions discussed here are small.

Subject Headings: Radioactive wastes | Silica | Material properties | Cement | Standards and codes | Calcium | Hydrologic models | Concrete | Nevada | United States

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