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Abstract

Introductory chapters review the state of the art in glass fibre reinforced cement (GRC) composites: the use of high alumina cement as a matrix is probably the most practical way of ensuring component compatibility in a GRC system.

Calculation of the theoretical tensile strength for different failure modes shows that there is considerable scope for improvement of the physical properties of GRC composites. On the other hand, analogous calculations applied to the various mechanisms available for absorbing energy in fracture produce far higher impact strengths than actually observed. The value of these calculations must not, however, be overrated as they are based on second-hand data, but they emphasise the need for a more detailed study of the glass fibre/cement interface.

An analytical method was developed for the rapid determination of A13+, Fe3+, Ca2+, OH- and pH in hydrating cement pastes which showed that both alkalinity and Ca2+ concentration were lower in high alumina than in portland cement. This should limit the gradual deterioration of the composite caused by direct chemical attack (weakening the fibres) and by disruptive internal crystal growth, but the relative importances of these two mechanisms still need to be resolved.

Preliminary single fibre pull-out experiments to determine interfacial bond strength indicated the need for tighter control over experimental variables. An apparatus was constructed for pulling glass fibres from the melt, thereby ensuring some control over their [surface: condition], and greater reliability was imparted to the pull-out system by the use of an Instron tensile tester. But despite allowance for the non-uniform distribution of interfacial stress, it was still impossible to get any better than qualitative results.

It was concluded that in GRC systems the interfacial stress would be better measured by a delamination type of test.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) T Technology > TH Building construction T Technology > TP Chemical technology
Departments:	School of Science & Technology > Department of Engineering Doctoral Theses

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