Effect of admixtures on the use of short fibres in structural concrete to enhance mechanical properties.

Abstract

Fibre-reinforced concrete is a term used when concrete is reinforced with randomly distributed short fibres. The addition of short fibres causes a reduction in workability. On the other hand, Superplasticisers can be used to increase the workability of concrete. The main objectives of the project were to investigate the effects of Superplasticisers on structural concrete with the addition of short-fibres, which vary from the most commonly used steel fibres, to polypropylene and fibre mesh. The behaviours of Superplasticisers on plain and fibre-reinforced concrete are compared. Lastly, data for the fresh and harden properties of the concrete were collected and analysed. The scope of this project is based on the usage of Superplasticisers in steel short-fibres, fibre mesh and polypropylene short-fibres. To evaluate the effects of Superplasticisers on the workability of fresh short-fibre reinforced concrete, several tests were carried out. These tests consist of slump tests Vebe tests and compacting factor tests. Meanwhile, the harden properties of concrete were assessed by the conducting tests, which involved compressive strength test, indirect-strength test, flexural strength test and finally test to determine the value for the modulus of elasticity. From the results of Vebe test and compacting factor test obtained, steel short-fibre reinforced concrete have the highest workability, which were followed by polypropylene short-fibre and Fibremesh reinforced concrete. Generally, when more then 1% of short-fibres are used to reinforce the concrete, rate of workability increases with the addition of Superplasticisers. Meanwhile, it was also found that flexural strength for fibre-reinforced concrete with the usage of Superplasticisers was higher.