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Micromechanical modelling of self-healing cementitious materials

Davies, Robert Elfed 2014. Micromechanical modelling of self-healing cementitious materials. PhD Thesis, Cardiff University.
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Abstract

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.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Engineering
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Uncontrolled Keywords: Micromechanical; Self-healing; Cementitious; Inelastic; Autogenous; micro-cracking.
Funders: Alun Griffiths Contractors, President's Scholarship
Date of First Compliant Deposit: 30 March 2016
Last Modified: 05 Jun 2017 04:51
URI: http://orca.cf.ac.uk/id/eprint/70424

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