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Sorption, anomalous water transport and dynamic porosity in cement paste: a spatially localised 1H NMR relaxation study and a proposed mechanis

McDonald, Peter, Istok, Ors, Janota, Magdalena, Gajewicz-Jaromin, Agata and Faux, David (2020) Sorption, anomalous water transport and dynamic porosity in cement paste: a spatially localised 1H NMR relaxation study and a proposed mechanis Cement and Concrete Research.

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Abstract

The link between anomalous water sorption and dynamic porosity in cement pastes is explored using spatially resolved GARField 1H nuclear magnetic resonance (NMR) relaxation analysis. A model is developed in which the effective capillary diffusion coefficient is dependent on the instantaneous pore size distribution. This and earlier data show changes in pore size distribution resultant from changes in saturation that do not occur instantaneously with changes in degree of saturation. Therefore, it is assumed that the pore size distribution is always relaxing exponentially towards a (saturation de pendent) equilibrium. It follows that the diffusivity is sample history (i.e.time) dependent as well as saturation dependent. This is sufficient to ex plain anomalies in rapid capillary water sorption. The same concepts are applied to slow drying. In this case, porosity changes occur on a timescale much shorter than drying so the system is always in dynamic equilibrium and anomalies are therefore not seen.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
NameEmailORCID
McDonald, PeterP.Mcdonald@surrey.ac.uk
Istok, Orsors.istok@surrey.ac.uk
Janota, Magdalenamagdalena.janota@surrey.ac.uk
Gajewicz-Jaromin, AgataAgata.Gajewicz@surrey.ac.uk
Faux, DavidD.Faux@surrey.ac.uk
Date : 17 March 2020
Funders : European Union Horizon 2020
Grant Title : Marie Sk lodowska-Curie In-781 novative Training Networks programme grant agreement
Uncontrolled Keywords : water sorption, diffusion, cement paste, anomalous transport
Depositing User : James Marshall
Date Deposited : 24 Mar 2020 15:13
Last Modified : 24 Mar 2020 15:13
URI: http://epubs.surrey.ac.uk/id/eprint/854077

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