The effects of different curing conditions on the polypropylene fibre reinforcement concrete

Abstract Due to technological advancements, the utilization of fibres and composites in improving the quality and serviceability of concrete structures has gained attention in recent years. Materials such as steel, glass and organic polymers have been used recently to produce short fibres deemed suitable for use in concrete production due to their ability to improve slab durability and prevent cracks in concrete. However, information about their ability to function under different curing conditions is still limited. This research examines the use of synthetic polypropylene fibre (Sika-Fibre 408X) of length 40mm in concrete by subjecting the concrete to four (4) different curing conditions. The curing conditions are ambient temperature, extreme heat of 165°C, extreme cold of -4°C and concrete cured under water temperature of 22°C. The control samples were prepared with no fibre while fibre concrete was made with 5% synthetic polypropylene fibre (Sika-Fibre 408X). Compressive and spilt tensile strength tests were performed on the samples after being cured under the said curing conditions for 14, 28 and 56 days. It was observed that the average compressive strength of fibre-reinforced concrete cured under the four various conditions for 14 days and 56 days is higher than the control sample, but the result obtained at 28 days of curing for all the curing conditions is contrary. The maximum compressive strength of 45.51 MPa was obtained for fibre-reinforced concrete cured under water at 22°C for 56 days. Likewise, for the split tensile test, the results showed that fibre-reinforced concrete has better strength compared to plain concrete under the four curing conditions. Furthermore, fibre-reinforced concrete cured at the extreme cold of -4°C for 56 days has the highest tensile strength of 2.93 MPa. However, for both plain and fibre-reinforced concrete, irrespective of the curing conditions and duration, the minimum compressive strength obtained for this research surpasses the compressive strength minimum requirement of 20 Mpa for cubic concrete according to the SANS 5863:2006.