Water Movement in Unsaturated Concrete: Theory, Experiments, Models

Leech, Craig Anthony (2003). Water Movement in Unsaturated Concrete: Theory, Experiments, Models PhD Thesis, School of Engineering, The University of Queensland.

       
Attached Files (Some files may be inaccessible until you login with your UQ eSpace credentials)
Name Description MIMEType Size Downloads
n01front.pdf n01front.pdf application/pdf 408.08KB 1
n02chapter1.pdf n02chapter1.pdf application/pdf 63.49KB 1
n03chapter2.pdf n03chapter2.pdf application/pdf 286.28KB 0
n04chapter3.pdf n04chapter3.pdf application/pdf 2.37MB 0
n05chapter4.pdf n05chapter4.pdf application/pdf 431.39KB 0
n06chapter5.pdf n06chapter5.pdf application/pdf 402.07KB 0
n07chapter6.pdf n07chapter6.pdf application/pdf 907.86KB 0
n08chapter7.pdf n08chapter7.pdf application/pdf 220.95KB 0
n09chapter8.pdf n09chapter8.pdf application/pdf 177.15KB 0
n10chapter9.pdf n10chapter9.pdf application/pdf 57.59KB 0
n11appendix.pdf n11appendix.pdf application/pdf 300.20KB 0
n12references.pdf n12references.pdf application/pdf 100.52KB 0
Author Leech, Craig Anthony
Thesis Title Water Movement in Unsaturated Concrete: Theory, Experiments, Models
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 2003
Thesis type PhD Thesis
Supervisor Lockington, D. A.
Total pages 316
Collection year 2003
Language eng
Subjects L
291100 Environmental Engineering
680299 Other
Abstract/Summary Prediction of contaminant transport in concrete subjected to short cyclical wetting and drying processes is integrally bound to prediction of the moisture flux. The concrete is unsaturated and the non-linear contaminant and moisture fluxes are not described by simple constant diffusion methods. This thesis presents, and partially justifies, a thermodynamic model for prediction of moisture movement in concrete, at all moisture contents commonly encountered. The wetting process is examined with Nuclear Magnetic Resonance (NMR) images during a simple absorption (sorptivity) experiment. Diffusivity functions are derived via a novel analytical approach and a universal diffusivity is suggested. Water sorption and desorption isotherms are measured on large concrete samples. van Genuchten’s retention function is successfully used to model the results. The unrelia-bility of the water sorption method at high moisture contents is illustrated by comparison with Mercury Intrusion Porosimetry (MIP). The BJH method is exploited to provide a methodology for estimating the water sorption isotherm from MIP. Mualem’s conductivity model is assessed with the water retention and NMR results. This thorough validation of the model yields a tortuosity parameter that is different to that commonly assumed. An analytical relationship between the sorptivity and the saturated permeability suggests the experimental the long-term unsaturated permeability overesti-mates the unsaturated conductivity function, and as such should be used judiciously when predicting unsaturated flow processes. Mualem’s conductivity model is further exploited to provide unsaturated air and vapour functions that are experimentally justified. The thermodynamic description of water movement and the hydraulic functions that are developed in the thesis are incorporated into T r inCet , a transient heat and mass trans-fer model based on the Finite Element Method (FEM). The complex coupled behaviour of air, liquid, vapour and temperature are well handled under a variety of common cyclical boundary conditions. The thesis presents all necessary experimental results required for validation of a com-plex, but easily described, model for moisture movement. It covers disparate ground to provide a powerful numerical model of unsaturated moisture movement in concrete under short-term cyclical processes.
Keyword sorptivity
NMR
concrete
water retention
moisture
MIP
unsaturated
permeability
numerical
FEM
water

 
Citation counts: Google Scholar Search Google Scholar
Access Statistics: 380 Abstract Views, 2 File Downloads  -  Detailed Statistics
Created: Fri, 21 Nov 2008, 17:17:54 EST