The roles of hydration and evaporation during the drying of a cement paste by localized NMR

• Published in: Cement and concrete research 2013-06, Vol.48, p.86-96
• Main Authors: Van Landeghem, Maxime, d'Espinose de Lacaillerie, Jean-Baptiste, Blümich, Bernhard, Korb, Jean-Pierre, Bresson, Bruno
• Format: Article
• Language: English
• Subjects: Accumulation; Applied sciences; Buildings. Public works; Capillarity; Cement concrete constituents; Cements; Condensed Matter; Drying; Drying (A); Evaporation; Exact sciences and technology; Humidity (A); Hydration; Hydration (A); Materials; Nuclear magnetic resonance; Pastes; Physics; Pore Size Distribution (B); Properties of anhydrous and hydrated cement, test methods; Soft Condensed Matter; Transport Properties (C)
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2013.01.012

The moisture distribution during the setting of a thin mortar layer can be particularly complex to manage under dry (20% RH) and hot weather (above 25°C) conditions. To better understand the fundamental phenomena at stake, we used static gradient relaxation NMR tools such as Profile MOUSE and STRAFI. This allowed disentangling the mutual effect of evaporation and self-desiccation by hydration. The interest of combining the two techniques is that the capillary water is observed with the MOUSE while STRAFI reveals quantitatively the build-up of the hydrate gel nanostructure. Spatially resolved and 2D relaxation exchange experiments on a model white cement paste revealed that although evaporation induced a capillary water gradient, the kinetics of the building of the pore structure and its homogeneity remained unaffected.