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Broad Line NMR Imaging: Applications to Porous Building Materials and New Developments in Stray Field Imaging.

Bohris, Alexander J. (1999) Broad Line NMR Imaging: Applications to Porous Building Materials and New Developments in Stray Field Imaging. Doctoral thesis, University of Surrey (United Kingdom)..

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A Fourier method of solving the Torrey-Bloch equations for nuclear magnetisation precession in a strong magnetic field gradient has been developed for the purpose of simulating the increasing number of pulse sequences now used in stray field experiments. The simulator explicitly includes the action of the gradient during Rf pulses and the effects of spin relaxation and diffusion. The method has been used to develop a novel one-shot pulse sequence, Dash, for measuring diffusion in the stray field independent of T2 relaxation. Three different strategies to obtain spatially resolved diffusion information using the Dash sequence are presented. It is demonstrated that very high resolution (a few um) diffusion profiles can be obtain with these methods. The results of a magnetic resonance relaxation analysis and broad line magnetic resonance imaging (gradient echo and SPRITE) study of water and water transport in Ordinary Portland Cement Pastes are presented. The effect of varying the cure conditions and the water to cement (w/c) ratio of the sample mix are discussed. Differences in the water transport behaviour between samples dried prior to exposure and non-dried samples are observed. These are particularly evident for 0.3 w/c ratio samples. The water sorptivity and the concentration dependence of the hydraulic diffusion coefficient are calculated for 0.5 and 0.3 w/c ratio samples. An attempt is made to model the experimentally obtained diffusivities using two water transport models found in the literature.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Bohris, Alexander J.
Date : 1999
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 1999.
Depositing User : EPrints Services
Date Deposited : 30 Apr 2019 08:08
Last Modified : 20 Aug 2019 15:33

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