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Investigation of a novel self-healing cementitious composite material system

Hazelwood, Tobias 2015. Investigation of a novel self-healing cementitious composite material system. PhD Thesis, Cardiff University.
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Abstract

This thesis describes a portion of the ongoing development of a novel self-healing cementitious material system named LatConX originally proposed by a group of researchers at Cardiff University. The research reported was undertaken with the aim of furthering understanding of the system’s long-term behaviour, ultimately with a view to providing predictions for the performance of the system over a structure’s working life. This aim is accomplished through a combination of experimental and numerical research. An experimental series is presented which investigates the stress relaxation behaviour of polyethylene terephthalate in order to establish how the stress induced by heat-activated restrained shrinkage varies with time. Results of these experiments displayed very little stress reduction from the peak stress, with less than a 5 % loss observed over a 124 day period. The development of a new one dimensional transient thermomechanical model for viscoelastic behaviour of pre-drawn polyethylene terephthalate is then described. This model is shown to be able to reproduce the observed experimental behaviour with good accuracy. The polymer model is coupled with a number of other constitutive models for the behaviour of steel and concrete, thus forming a model for the material system as a whole. This coupling is undertaken within the framework of an idealised simply supported beam with a strong discontinuity for the simulation of a central crack hinge. The model is validated against experimental data and design code predictions. Design considerations for the LatConX system are discussed and modified design equations derived. Parametric studies are presented investigating the structural performance and material costs of beams incorporating the LatConX system compared with that of standard reinforced concrete beams. Encouraging results are reported suggesting that the LatConX system has the potential to simultaneously improve long-term durability and structural performance of reinforced concrete structures and reduce the initial material costs by replacing a percentage of the reinforcing steel with shape memory polymer.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Engineering
Subjects: T Technology > TH Building construction
Uncontrolled Keywords: Cementitious material; Self-healing; Reinforced concrete; Shape memory polymer; Numerical modelling.
Funders: EPSRC, BRE
Date of First Compliant Deposit: 30 March 2016
Last Modified: 21 Oct 2016 05:22
URI: http://orca.cf.ac.uk/id/eprint/76766

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