Cement/clay interactions – A review: Experiments, natural analogues, and modeling

Abstract

The concept of storing radioactive waste in geological formations calls for large quantities of concrete that will be in contact with the clay material of the engineered barriers as well as with the geological formation. France, Switzerland and Belgium are studying the option of clayey geological formations. The clay and cement media have very contrasted chemistries that will interact and lead to a degradation of both types of material. The purpose of this review is to establish an exhaustive list of laboratory experiments so as to identify the reaction sequences in the evolution of both the clay minerals and accessory minerals during their alteration in an alkaline environment. We review the data on clay dissolution kinetics in this environment, and include an invaluable study of natural analogues that allow one to correlate the phenomena in time. The available data and experiments make it possible to construct predictive numerical models. However, as the quality of the data is inhomogeneous, we recommend a continuation of the thermodynamic and kinetic data acquisition. It is obvious that the numerical modeling of the alkaline disturbance will be more relevant if it can combine the advantages of the different detailed models: mineralogical completeness, combined modeling of the clay and cement media, evolution of the porosity, consideration of the pCO 2 and all the surface reactions.

Deformation and Compression Behaviour of a Cement–Bentonite Slurry for Groundwater Control Applications

“…The cementitious products (Portlandite, CSH, CASH, etc.) are chemically stable at high pHs but will dissolve and reform as other products with reducing pH: Portlandite will degrade below a pH of 12.4 and the CSH gel will degrade below a pH of 10 (Gaucher and Blanc 2006). For example, Rimmele and Barlet-Gouedard (2010), who exposed various concrete samples to fluids supersaturated with carbon dioxide (driven into the concrete samples using electrokinetics, thus reducing the pH of the pore fluid), observed dissolution of the CSH, due to decalcification, and precipitation of carbonates associated with penetration of the dissolved carbon dioxide.…”

“…For example, Rimmele and Barlet-Gouedard (2010), who exposed various concrete samples to fluids supersaturated with carbon dioxide (driven into the concrete samples using electrokinetics, thus reducing the pH of the pore fluid), observed dissolution of the CSH, due to decalcification, and precipitation of carbonates associated with penetration of the dissolved carbon dioxide. Conversely, the smectitic minerals within the bentonite are likely to experience degradation at higher pH levels (Gaucher and Blanc 2006).…”

Reactive transport modeling for CO2 geological sequestration

“…Geloni et al (2011) performed the numerical modeling to investigate the rock-cement alterations driven by the injection of CO 2 . Their simulations were able to predict the main mineralogical alterations occurring at the cement-reservoir and cement-caprock interfaces as documented in the literature (as muscovite dissolution and zeolites and brucite precipitation, Gaucher and Blanc, 2006). The cement alterations due to CO 2 brine acidification are very localized at the rock domain interfaces.…”

Generic Argillite/Shale Disposal Reference Case

“…Because a concrete liner is emplaced between the bentonite backfill and argillite host rock, concrete/bentonite and concrete/argillite interactions are potentially important. Experimental and modeling studies of concrete/bentonite interaction are reviewed in Gaucher and Blanc (2006). Kosakowski and Berner (2013), Gaboreau et al (2012), andDe Windt et al (2008) provide modeling studies of concrete/argillite interactions.…”