Influence of Long Polypropylene Fibre on the Properties of Concrete

Concrete is the most used building and construction material globally due to the ease of availability and durability. It is a well-known fact that concrete can easily withstand compressive stresses; however, it fails under tension. To improve this deficiency, steel bar reinforcement has been used. However, with the steel reinforcement, additional permanent self-weight is transferred on the structure and is prone to corrosion. Hence, engineers and researchers have been working to search for more sustainable reinforcing material that could be cost-effective and simultaneously increase tensile strength. This experimental work was carried out to study the influence of long (38.1 mm) polypropylene (PP) fibres on the workability and mechanical strengths (compressive and flexural) of concrete. Three different fibre fraction content, 0.20%, 0.25% and 0.30% were selected to reinforce concrete. A total of 12 cylinders of 300mm×150mm dimension (3 cylinders per mix) and 12 beams of 609.6mm×304.8mm×101.6mm dimension (3 beams per mix) were used to determine the compressive strength and flexural strength after the samples achieved 28 days curing. Based on the results, it can be observed that longer fibres do not significantly influence the compressive strength as much as they do on flexural strength. Furthermore, longer length fibres, like shorter fibres, obstruct the workability of concrete. Comparing with previous findings, it can be concluded that for patching of macrocracks, longer length PP fibres should be used.