Impact of a 70 °C temperature on an ordinary Portland cement paste/claystone interface: An in situ experiment

Journal Article · Sun May 15 04:00:00 EDT 2016 · Cement and Concrete Research

DOI:https://doi.org/10.1016/J.CEMCONRES.2016.02.001· OSTI ID:22696557

Lalan, Philippines ^[1]; Dauzères, Alexandre ^[1]; Bartier, Danièle ^[2]; Sammaljärvi, Juuso ^[3]; Barnichon, Jean-Dominique ^[1]; Techer, Isabelle ^[4]; Detilleux, Valéry ^[5]

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1. Institute of Radiation Protection and Nuclear Safety (IRSN)/PRP-DGE/SRTG/LETIS, BP 17, 92262 Fontenay-aux-Roses Cedex (France)
2. CNRS UMR 7566, Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy (France)
3. Laboratory of Radiochemistry HYRL, Department of Chemistry, University of Helsinki, PO Box 55, 00014 (Finland)
4. University of Nimes, EA 7352 CHROME, rue du Dr Georges Salan, 30021 Nîmes (France)
5. Bel V, 148 Rue Walcourt, 1070 Anderlecht (Belgium)

Radioactive wastes in future underground disposal sites will induce a temperature increase at the interface between the cementitious materials and the host rock. To understand the evolution of Portland cement in this environment, an in situ specific device was developed in the Underground Research Laboratory in Tournemire (France). OPC cement paste was put into contact with clayey rock under water-saturated conditions at 70 °C. The initial temperature increase led to ettringite dissolution and siliceous katoite precipitation, without monosulfoaluminate formation. After 1 year of interaction, partial decalcification and diffuse carbonation (calcite precipitation) was observed over 800 μm in the cement paste. At the interface, a layer constituted of phillipsite (zeolite), tobermorite (well-crystallised C-S-H) and C-(A)-S-H had formed. Globally, porosity decreased at both sides of the interface. Geochemical modelling supports the experimental results, especially the coexistence of tobermorite and phillipsite at 70 °C, minerals never observed before in concrete/clay interface experiments.

• OSTI ID: 22696557
• Journal Information: Cement and Concrete Research, Journal Name: Cement and Concrete Research Vol. 83; ISSN CCNRAI; ISSN 0008-8846
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CARBONATES
INTERFACES
PORTLAND CEMENT
PRECIPITATION
RADIOACTIVE WASTES
UNDERGROUND DISPOSAL
WATER