Experimental and numerical study of the fracture and self-healing of cementitious materials

Joseph, Christopher 2008. Experimental and numerical study of the fracture and self-healing of cementitious materials. PhD Thesis, Cardiff University.

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Abstract

This thesis presents details of an experimental and numerical programme of study undertaken on the fracture and self-healing of cementitious materials at Cardiff University. The experimental component reported in the thesis consists of an extensive programme of tests conducted on reinforced mortar specimens, autonomically healed with a low viscosity cyanoacrylate adhesive. The development of the self-healing experimental procedure is explained and results of a series of three point bending tests are presented. These examine the effect of reinforcement, pre-notching, and rate of loading, on the healing performance of the beams. Both primary and secondary healing behaviour was observed during the first and second loading cycles, respectively. The numerical component of this thesis describes development work undertaken on the discrete lattice beam modelling method. The aim of these developments is to improve the quantitative aspects of the model, including mesh orientation and size dependency, and over-brittleness of the force-displacement response. The orientation effect of the lattice is discussed and various failure criteria which minimise, or omit, this effect are presented and compared. The effect of mesh size (lattice resolution) on the specific fracture energy is also examined. A new regularisation method, which is based on the application of statistical distributions of beam strengths that are linked to the beam length, is presented. This method is shown to significantly improve the objectivity of the force-displacement results, whilst maintaining the qualitative ability to capture the main phases of crack formation, namely macrocrack growth, crack branching and bridging. In the final chapter the lattice method is used to simulate the self-healing response observed during the experiments. The method was found to be capable of capturing realistic pre- and post-healing fracture patterns, in addition to the stiffness increase observed during primary healing, which occurs shortly after the release of adhesive from the glass supply tubes.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Engineering
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
ISBN:	9781303215414
Date of First Compliant Deposit:	30 March 2016
Last Modified:	03 Mar 2020 02:51
URI:	https://orca.cardiff.ac.uk/id/eprint/54913

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