Chemical and mineralogical characterizations of a low-pH cementitious material designed for the disposal cell of the high-level radioactive waste (HLW). (December 2022)

• Record Type: Journal Article
• Authors: Bonnet, J.; Mosser-Ruck, R.; Sterpenich, J.; Bourdelle, F.; Verron, H.; Michau, N.; Bourbon, X.; Linard, Y.
• Is Part Of: Cement and concrete research. Volume 162(2022)
• Publication Date: 2022-12
• Subjects: Radioactive waste management -- Low-pH cement -- Calcium-silicate-hydrate (C-S-H) -- SEM and X-ray diffraction characterizations; Cement -- Periodicals; Cement -- Research -- Periodicals; Concrete -- Periodicals; Concrete -- Research -- Periodicals; Ciment -- Périodiques; Béton -- Périodiques; Cement; Concrete; Periodicals; 620.135
• DOI: 10.1016/j.cemconres.2022.107013
• Languages: English
• ISSNs: 0008-8846

Abstract

Abstract: This paper presents the chemical and mineralogical characterizations of a cementitious material and its behaviour to temperature increase in conditions close to those of radioactive waste storage. The formulation, based on a CEM III/C, silica fume, bentonite and hydrotalcite makes a low-pH cementitious grout with a low viscosity. Results show that the mineralogical composition of this material evolves during setting. Two years after setting, it is a macro porous geomaterial, composed of few C-(A)-S-H with a low C/S ratio (<0.4) formed from the blast furnace slags. It also contains well-crystallized ettringite, hydrotalcite, calcite and still non hydrated C2S. In contact with air, a substantial enrichment in calcite and gypsum is observed. The heating up to 90 °C leads to the transformation of the Na-rich smectite of the bentonite into a Ca and/or Mg-rich one and the formation of opal-CT, vaterite and aragonite. Hydrotalcite is stable whereas gypsum and anhydrite disappear.