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Modelling the effect of microcracks on transport properties of concrete

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Title: Modelling the effect of microcracks on transport properties of concrete
Authors: Dehghanpoor Abyaneh, Saeed
Item Type: Thesis or dissertation
Abstract: The main objective of this thesis is to develop three-dimensional numerical models to predict transport properties of concrete from its internal structure. The models relate the macroscopic transport property to internal structure of concrete so a better understanding of the influence of microstructure, especially microcracks, on transport properties can be obtained. Diffusivity of concrete is modelled by combining a digitised mesostructure and finite difference algorithm. This allows the determination of the effect of microcracks, ITZ and aggregate shape on the diffusivity of mortar and concrete. The limitation of this approach in modelling very small features (several micrometres) is discussed. A finite element technique is coupled with aligned meshing approach to study the effect of microcracks on the diffusivity of concrete. Microcracks are incorporated as interface elements. New information regarding the effect of microcrack properties such as width, density, diffusivity and percolation on overall diffusivity of concrete is obtained. The transport model is then combined with a mechanical model to investigate the effect of tensile load-induced microcracks on diffusivity. In doing so, the mechanical model is used to simulate the formation and propagation of microcracks due to tensile loading which is then used as an input to the transport model. A similar technique is applied to investigate the effect of microcracks on the permeability of concrete. The simulations show the influence of microcrack properties such as width, density and percolation on overall permeability of concrete. The difference between the effect of microcracks on permeability and diffusivity is discussed. Capillary absorption of concrete is modelled by using a Lattice-Network approach in which unsaturated flow is simulated using a non-linear finite element method. The model is employed to evaluate the effect of heterogeneities produced by aggregate particles and microcracks on the sorptivity of concrete.
Content Version: Open Access
Issue Date: Mar-2015
Date Awarded: Oct-2015
URI: http://hdl.handle.net/10044/1/30847
DOI: https://doi.org/10.25560/30847
Supervisor: Buenfeld, Nick
Wong, Hong
Sponsor/Funder: European Commission
Funder's Grant Number: 26448
Department: Civil and Environmental Engineering
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Civil and Environmental Engineering PhD theses

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