Modeling of leaching from cementitious materials used in underground environment
Source abstract
Abstract
Abstract The purpose of this research is to evaluate the long-term durability of engineered barrier materials used in underground radioactive waste disposal facilities. Radioactive waste repositories are constructed in crystalline rocks, sedimentary rocks, or clay, which are natural barrier materials, using bentonite and/or cementitious materials as additional engineered barriers in those natural barriers. These engineered barriers are required to inhibit leakage of radionuclides for a long period of more than 1000 or 10,000 years. This necessitates the actual evaluation of long-term durability and quantitative evaluation of the interactions of each of these barrier materials. Cementitious materials are considered to come in contact with underground water or bentonite and release alkali components, which may degrade their performance. Furthermore, there is apprehension that the properties of bentonite may be altered due to the effect of alkaline components included in cementitious materials. In view of the above, the estimation of changes with time of various components that leach out of cementitious materials is considered to be important for evaluating the long-term performance of engineered barriers. The authors firstly carried out leaching experiments considering temperature effects to construct a solubility equilibrium model of cement hydrate. Next, leaching of calcium from concrete was modeled using this solubility model and an advection–diffusion model. Furthermore, the degradation due to leaching of actual structures, from 34 to 104 years old, was studied, and it was observed that a degradation of 100 mm maximum occurs over a period of 100 years. The calculated results of the proposed model showed very good agreement with the results of studies on actual structures. Finally, the effects of various factors on the degradation rate were evaluated numerically using this model. In addition, a simple evaluation of the degradation of bentonite was also performed.
Source: openaire · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Concrete and Cement Materials Research · Nuclear materials and radiation effects · Recycled Aggregate Concrete Performance
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References (13)
Show source-provided references
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