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Abstract

Steel fibre reinforced concrete (SFRC) has been in the construction industry since decades, and more recently has become a highly demanded product. Issues with its implementation on the field, related to workability have always been present. Anyways, the mechanical performance improvements for SFRC are quite considerable; therefore, research to assess the effective factors of steel fibres influencing the SFRC needs to be done. This project investigates how the steel fibres geometry (length and diameter) directly affects the SFRC properties in fresh and hardened state.
To assess the research’s aim, the steel fibre addition wasn’t done by volumetric weight, instead it was made by equal fibre count dosage in the concrete with four fibres possessing different dimensions but the same shape and material properties. The steel fibres used were 3D type with hooked-end shape and lengths of 30, 35, 50, and 60 mm. 9 different mixes, one control without steel fibres and eight containing steel fibres were prepared: dividing the mixes with steel fibre addition into two groups of 190,674 and 233,046 fibres per cubic meter of concrete.
SFRC 100x100x100 mm cubes and 150x150x600 mm beams were produced to be subjected to slump cone, compressive, and 3-point bending tests. The results showed that the longest steel fibres of 50- and 60- mm length had the most negative impact on the workability, with reductions of up to -100% against the slump value of the control mix. For the compressive strength the steel fibres addition did not affect the results significantly, the best improvement was seen for the 50 mm length fibre with 4.08%. Finally, on the flexural performance aspect very significant improvements were observed, the optimum steel fibre was the 50 mm length at 233,046 fibres/m3 dosage where the flexural strength was enhanced up to a 120%. The limit of proportionality, residual flexural strength, and flexural energy were considerably boosted too by the longest steel fibres of 50 and 60 mm.
It was concluded that the steel fibre length and diameter is a determining factor for the steel fibre reinforced concrete performance of workability and mechanical properties. The best steel fibre results for the SFRC (including the workability aspect) was handed by the 50 mm length fibre, instead of the 60 mm length. The difference was that the 50 mm length fibre had a 16.67% bigger diameter, influencing positively in all the mechanical performance tests.

Course: Civil Engineering - MSc - C0618

Date Deposited: 2023-11-07

URI/permalink: https://library.port.ac.uk/dissert/dis14255.html