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Magnetic Resonance Imaging Characterisation of Water Transport in Cement-Based Materials.

Zamani, Sahar. (2013) Magnetic Resonance Imaging Characterisation of Water Transport in Cement-Based Materials. Doctoral thesis, University of Surrey (United Kingdom)..

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Abstract

This work addresses a better understanding of water dynamics in cement paste and mortar materials. Permeability to water and water transport diffusion are measured using magnetic resonance profiling. Water self diffusion in one and two dimensions is measured using nuclear magnetic resonance pulsed field gradient diffusometry. With regard to water permeability of cement paste and mortars, three topics are addressed. The permeability is measured as a function of relative humidity for cement pastes of different sizes and as a function of sand size for mortars. The relative liquid water and water vapour permeability are calculated using a modified version of a model suggested by Baroghel-Bouny et al. The intrinsic permeability values for cement pastes are similar to those measured by beam bending methods by Vichit-Vadakan and Scherer. The values found for mortars are similar to those measured by Baroghel-Bouny et al. The time dependence of the equilibration of the water concentration profile is also measured. With regard to water transport diffusion, mortars with different sand sizes are studied during water ingress/egress cycles. It is shown that ingress of water into dried mortars slows dramatically after some time most likely due to pore blocking by particulate fines carried with the water. Two indicative transport diffusion coefficients are obtained corresponding to the water diffusion before and after the blockage is encountered. With regard to diffusometry, the water self-diffusion coefficient was measured in a cement paste and found to decrease rapidly in the early stages of hydration. The capillary pore size distribution is measured from an analysis of restricted diffusion data in a mature sample. No evidence of capillary pore anisotropy is found.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Zamani, Sahar.
Date : 2013
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2013.
Depositing User : EPrints Services
Date Deposited : 14 May 2020 15:43
Last Modified : 14 May 2020 15:47
URI: http://epubs.surrey.ac.uk/id/eprint/856839

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