Physico-chemical investigation of clayey/cement-based materials interaction in the context of geological waste disposal: Experimental approach and results

5-year chemico-physical evolution of concrete–claystone interfaces, Mont Terri rock laboratory (Switzerland)

“…This may lead to mineralogical alteration in the barrier system which in turn is expected to locally influence properties like porosity/permeability, swelling pressure or specific retention properties in case of concrete in contact with claystone or compacted bentonite. Laboratory experiments (Adler 2001;Adler et al 2001;Dauzeres et al 2010) and in situ experiments (Read et al 2001;Tinseau et al 2006;Gaboreau et al 2011Gaboreau et al , 2012Techer et al 2012;Jenni et al 2014) demonstrate alteration of both cement paste and claystone adjacent to interfaces. An increase in porosity in the cement paste close to the interface, and clogging in the claystone adjacent to it are commonly predicted by reactive transport modelling (De Windt et al 2008;Marty et al 2009;Kosakowski and Berner 2013;Bradbury et al 2014).…”

Contribution to the French program dedicated to cementitious and clayey materials behavior in the context of Intermediate Level Waste management – Hydrogen transfer and materials durability

“…Cementitious materials are exposed to a solution representative of the clayey geological layer (multi-ionic attack) or directly to the natural clay (specific device ABIE able to keep the confinement of clay in contact with cement paste) (Figure 4a). In particular, the PhD study of A. Dauzères [12] allowed to show that transport properties of the degraded zone are altered, due to the clogging of the porosity linked to the precipitation of calcite (Figure 4b). 05001-p.5…”

“…The degradation front, characterized by a depletion of the portlandite and the precipitation of calcite has been evidenced. Thus a phenomenological modeling based on chemo-transport processes has been proposed [9].…”

“…4. a) ABIE specific device developed for contact between cementitious and clayey materials, b) Macroporosity profile calculated by image analysis from X-ray tomography measurements (1 yr test) [12].…”

Inhibition of the formation and stability of inorganic colloids in the alkaline disturbed zone of a cementitious repository

“…While the cement will buffer the pore water to a highly alkaline pH, this could potentially create an alkaline plume penetrating from the repository into the host rock, perturbing the chemistry within a zone referred to as alkaline disturbed zone (ADZ). The alkaline cement leachate can react with the host rock, promoting dissolution of some mineral phases, precipitation of new phases (Daizeres et al, 2010) and the generation of colloids (Mashal et al, 2004) that may affect radionuclide movement within the chemically disturbed zone of the host rock. The nature, stability and mobility of the colloids in the ADZ have been identified as sources of uncertainty in the performance assessment of a cementitious GDF (Swanton et al, 2009).…”