This thesis presents details of a numerical programme of study on the themo-hygrochemical (THC) processes occurring during the self-healing of cementitious materials. A comprehensive THC model, which is mechanistic in nature, is proposed and implemented in the framework of the finite element method. The aim of this model is to develop a useful computational tool that is capable of realistically predicting damage recovery in terms of the crack filling observed under specific environmental conditions. The early age and long term behaviour of the cementitious materials is simulated by solving a boundary value problem which couples moisture-temperature-ion transport mechanisms by means of mass and enthalpy balance equations. The model assumes that all the transport processes occur at the capillary pore level and that the selfhealing is driven by ongoing hydration. In this context, attention is focused on developing an innovative microstructural model that can predict the quantitative evolution of the capillary porosity. The microstructural model is based on an existing colloidal classification of the water forms present in the clinker hydrates, on hydration kinetics principles and on the stoichiometry of the Portland cement. The effect of the aggregate absorption on the capillary porosity is also examined. Firstly, the adopted theoretical considerations regarding the transport of moisture and temperature in cement-based materials are validated by comparing the numerical findings of the TH component with the reported results of three different sets of drying experiments. Then the THC model is applied to the simulation of a crack recovery experiment undertaken at Cardiff University. In both cases the proposed model was found to capture the essential characteristics of the thermo-hygro-chemical behaviour of cementitious materials.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:637148 |
| Date | January 2014 |
| Creators | Chitez, Adriana |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/70906/ |
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