The effect of Ordinary Portland Cement on nuclear waste glass dissolution

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Abstract

To evaluate the durability of the glass matrix and to identify the key mechanisms responsible for glass alteration in the cementitious environment imposed by the Supercontainer design, glass leach tests were conducted at 30°C under Ar atmosphere in suspensions of Ordinary Portland Cement and synthetic young cement water with the high pH of 13.5. The cement appears to trigger the glass dissolution by consumption of glass matrix components leading to a fast glass dissolution at a constant rate with the formation of a porous gel layer on the glass. The key mechanism driving the long-term glass dissolution is secondary phase formation with Si and Al from the glass matrix. The two main reactions are the reaction of Si released by the glass with portlandite, leading to the formation of Calcium Silicate Hydrate (C-S-H) phases, and the further conversion of C-S-H phases with Al from the glass to form Calcium Aluminum Silicate Hydroxide (C-A-S-H) phases. After consumption of the portlandite, the glass alteration rate is expected to decrease

Details

Original languageEnglish
Pages (from-to)223-229
JournalProcedia Materials Science
Volume7
DOIs
Publication statusPublished - Dec 2014
Event2nd International Summer School on Nuclear Glass Wasteform: Structure, Properties and Long-Term Behavior, SumGLASS 2013 - CEA-AREVA Joint Vitrification Lab, site du Pont du Gard, France
Duration: 23 Sep 201327 Sep 2013

Keywords

  • Supercontainer design, Ordinary Portland Cement, glass dissolution, hyperalkaline pH, pozzolanic reaction

ID: 272171