Magnesium perturbation in low-pH concretes placed in clayey environment - Solid characterizations and modeling

A. Dauzeres (1) , G. Achiedo (1) , D. Nied , E. Bernard , S. Alahrache , B. Lothenbach

1 IRSN/PRP-DGE/SRTG/LETIS - Laboratoire d'Etude et de recherche sur les Transferts et les Installations dans les Sols

In the framework of the CI project, the interaction of two different low-pH cements (ESDRED and LAC) with Opalinus Clay (OPA) at Mont-Terri rock laboratory was studied. SEM-EDS analyses showed after 2.5 and 5 years of interaction a Mg-enriched zone associated with a decalcification of the C-S-H near the OPA contact zone of both cements. TGA and XRD investigations indicate that hydrotalcite and brucite predict classically in modeling are not formed. 29Si NMR and FTIR analyses showing a high polymerization degree of the Si-network typical of a sheet-like structure as observed for M-S-H. TEM/EDS investigations of the Mg enriched zone of both concretes indicate that the formed Mg phase exhibits a gel-like structure. New reactive transport modeling with the HYTEC code corroborates the formation of M-S-H at the interface. © 2015 Elsevier Ltd.

Domaines: Sciences de l'ingénieur [physics]

A. Dauzeres, G. Achiedo, D. Nied, E. Bernard, S. Alahrache, et al.. Magnesium perturbation in low-pH concretes placed in clayey environment - Solid characterizations and modeling. Cement and Concrete Research, 2016, 79, pp.137-150. ⟨10.1016/j.cemconres.2015.09.002⟩. ⟨hal-02557566⟩