Effect of aqueous solution chemistry on the swelling and shrinkage of the Tournemire shale

Investigations of Near-Field Thermal-Hydrologic-Mechanical-Chemical Models for Radioactive Waste Disposal in Clay/Shale Rock

“…Although the possible change in clay-rock swelling properties which has been demonstrated with short term and small-scale lab tests (Thury, 2002;Wakim et al, 2009) and by indirect measurement (such as the occurrence of illitization- Kamei et al, 2005;Cuadros, 2006) point out the need to evaluate the geochemically induced swelling/shrinkage of host clay rock, no such evaluation has been reported, as far as our literature survey has found. In this report, coupled THC models that include EBS and host clay rock are linked with a swelling model based on the Gouy-Chapman diffuse double layer (DDL) theory, in which the changes in swelling properties within the nearfield area of host clay rock are evaluated.…”

“…The swelling properties of the near-field host clay rock might change due to geochemical reasons (Thury, 2002;Wakim et al, 2009), including a change in ion concentration, exchangeable cations, or the amount of swelling clay minerals. Host clay rock, especially in the near-field area, undergoes geochemical changes due to the interaction between EBS and host clay rock, as demonstrated by THC models for EBS and host rock (Liu et al, 2010).…”

“…More highly mineralized waters result in smaller swelling heaves by 2% only. Wakim et al (2009) experimentally evaluated the effect of aqueous solution chemistry on the swelling and shrinkage of shales under saturated conditions, and reported that the more concentrated solution led to less swelling of shale. Kamei et al (2005) and Cuadros (2006) indicated that illitization, the transformation from smectites to illite, is usually part of the diagenesis process of clay formation.…”

Investigation of Reactive Transport and Coupled THMC Processes in the EBS

“…However, those published laboratory tests (e.g. Di Maio, 1996;Wakim et al, 2009) typically lack detailed characterization of the geochemical parameters such as mineralogical and aqueous composition, which makes it difficult to find a suitable laboratory test.…”

On the Definition of an Effective Stress for Shales

“…However, extensive experimental campaigns performed on fine-grained soils (among others: Di Maio and Fenelli, 1994;Witteveen et al, 2013;Manca et al, 2016) and on shales (among others: Wong, 1998;Wakim et al, 2009;Ewy, 2014Ewy, , 2015Favero, 2017) show a dependence of their shear strength and their volumetric behaviour on the solute suction of the aqueous solution used to test them. Some of the aforementioned works has led researchers of the past to define expressions of effective stress as a function of electrochemical stresses (a review is given in Hueckel, 1992); these expressions -being derived at the particle scale by imposing mechanical equilibrium and compatibility equations -should be more correctly called inter-particle stresses and, although used at the REV scale, remain of limited practical use.…”