This research has examined the two largest potential markets
for melt extract stainless steel fibres, namely sprayed concrete and
refractory concrete. An emphasis was placed on developing appropriate
test methods that would produce experimental data of a practical and
useful nature. A comparison was made at various stages between melt
extract fibres and more conventional drawn wire fibres.
The spraye~ concrete programme studied three fibre dispersion
techniques on site and produced test panels between 50mm and 150mm
thick from which beam and core specimens were cut. Information was
obtained on fibre rebound and the effects of specimen age, fibre
type and content on compressive, flexural and splitting strengths
and toughness. Rebound of drawn wire fibres was found to be twice
that of melt extract fibres on plywood panels and approaching two
and a half times greater on rock. The addition of steel fibres
produced increases in compressive and flexural strengths, typical
values for a 7.5% dry mix content being 15% and 55% respectively.
Two splitting tests on cores (Brazilian and point-load types) were
investigated as possible methods of on site quality control and
results indicated linear relationships between flexural and splitting
strengths. The post-crack toughness was examined in terms of the
area under the beam load/deflection curve and a computer programme
was used to evaluate a variety of toughness indices. Deflection
cut-off crieria based on the ultimate load co-ordinates or fixed
values of deflection were found preferable to those calculated from
the first crack deflection and the use of the elastic area under
the fibrous beam's curve as the denominator of the index proved
less reliable than using that of the unreinforced material. The
inclusion of 7% by weight of melt fibres increased the toughness
by over 30 times when using the 2.3mm fixed deflection criteria. [... continued].
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.