Nuclear magnetic relaxation dispersion investigations of water retention mechanism by cellulose ethers in mortars

Laetitia Patural (1, 2, 3) , Jean-Pierre Korb (4) , Alexandre Govin (1, 3, 5) , Philippe Grosseau (1, 3, 5) , Bertrand Ruot (6) , Olivier Devès (6)

1 SPIN-ENSMSE - Centre Sciences des Processus Industriels et Naturels
2 P2MC-ENSMSE - Département Poudres et Matériaux Multi-Composants
3 LPMG-EMSE - Laboratoire des Procédés en Milieux Granulaires
4 LPMC - Laboratoire de physique de la matière condensée
5 PROPICE-ENSMSE - Département PROcédés Poudres, Interfaces, Cristallisation et Ecoulements
6 CSTB - Centre Scientifique et Technique du Bâtiment

We show how nuclear magnetic spin-lattice relaxation dispersion of proton-water (NMRD) can be used to elucidate the effect of cellulose ethers on water retention and hydration delay of freshly-mixed white cement pastes. NMRD is useful to determine the surface diffusion coefficient of water, the specific area and the hydration kinetics of the cement-based material. In spite of modifications of the solution's viscosity, we show that the cellulosic derivatives do not modify the surface diffusion coefficient of water. Thus, the mobility of water present inside the medium is not affected by the presence of polymer. However, these admixtures modify significantly the surface fraction of mobile water molecules transiently present at solid surfaces. This quantity measured, for the first time, for all admixed cement pastes is thus relevant to explain the water retention mechanism.

Mots clés: Cellulose ether; Cement paste; NMR relaxometry; Surface diffusion coefficient; Water retention

Domaines: Génie des procédés

Laetitia Patural, Jean-Pierre Korb, Alexandre Govin, Philippe Grosseau, Bertrand Ruot, et al.. Nuclear magnetic relaxation dispersion investigations of water retention mechanism by cellulose ethers in mortars. Cement and Concrete Research, 2012, 42 (10), pp.1371-1378. ⟨10.1016/j.cemconres.2012.06.002⟩. ⟨hal-00762106⟩