Cement/clay interactions-- a review: experiments, natural analogues, and modeling

Area of Science:

• Geochemistry
• Materials Science
• Nuclear Waste Management

Background:

• Radioactive waste disposal in geological formations requires concrete in contact with clay barriers.
• Clay and cement exhibit contrasting chemistries, leading to material degradation.
• France, Switzerland, and Belgium are investigating clay formations for waste storage.

Purpose of the Study:

• To compile laboratory experiments on clay-mineral and accessory-mineral alteration in alkaline environments.
• To identify reaction sequences during clay-cement interactions.
• To inform predictive numerical modeling for radioactive waste disposal.

Main Methods:

• Review of laboratory experiments on clay-mineral and accessory-mineral alteration.
• Analysis of clay dissolution kinetics in alkaline conditions.
• Inclusion of natural analogue studies to correlate phenomena over time.

Main Results:

• Identified reaction sequences in clay and accessory mineral alteration under alkaline conditions.
• Highlighted the importance of natural analogues for temporal correlation.
• Demonstrated the potential for constructing predictive numerical models.

Conclusions:

• Existing data quality is inhomogeneous, necessitating further thermodynamic and kinetic data acquisition.
• Numerical modeling of alkaline disturbance requires integration of various models (mineralogical completeness, clay-cement interaction, porosity, pCO2, surface reactions).
• Enhanced data acquisition will improve the relevance of numerical models for radioactive waste disposal.