A self-healing cementitious material could provide a step change in the design of concrete structures. There is a need to understand better the healing processes, to predict accurately experimental behaviour and to determine the impact on mechanical properties. Micromechanical modelling, with a two-phase Eshelby inclusion solution, is chosen as a suitable framework within which to explore self-healing. The impact of micro-cracking and other time-dependent phenomena are considered alongside self-healing experiments and the numerical mechanical strength response. A new approach describes simulating inelastic behaviour in the matrix component of a two-phase composite material. Quasi-isotropic distributed micro-cracking, accompanying volumetric matrix changes, is combined with anisotropic microcracking arising from directional loading. Non-dilute inclusions are homogenised and an exterior point Eshelby solution is used to obtain stress concentrations adjacent to inclusions. The accuracy of these solutions is assessed using a series of three dimensional finite element analyses and a set of stress/strain paths illustrate the model’s characteristics. The problem of autogenous shrinkage in a cementitious composite is applied using a volumetric solidification and hydration model, which quantifies the effects of micro-cracking. Experiments on early age concrete and mortar beams showed that autogenous healing is primarily due to continued hydration. A novel self-healing model focuses on mechanical strength recovery of micro-cracked material and considers healing whilst under strain as well as allowing for re-cracking the healed material. The constitutive model is combined with a layered beam model to allow successful comparisons with experimental results.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:637133 |
| Date | January 2014 |
| Creators | Davies, Robert Elfed |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/70424/ |
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