Fire Response and Mechanical Performance of Fibre-Reinforced Concrete Incorporating Recycled Plastic Fibres

Abstract

Effect of fire on buildings has been a major concern in the world today. The integrity of concrete is usually questioned due to the fact that after fire outbreaks, the strength of the concrete is reduced considerably. In this study, fire resistance characteristics of Fibre Reinforced Concrete were investigated and plastic fibre was used to achieve this feat. Particle size analysis was conducted for both fine and coarse aggregates. Plastic fibers were produced from waste plastic water bottles using shredding machine and used at 1, 1.5 and 2% volume fractions. The mix proportion used was 1:2:4 of cement, fine aggregate and coarse aggregate. Slump, compressive strength, and fire resistance tests were performed on concrete specimens. The compressive strength tests were conducted at 7, 14, 21, and 28 days, while the fire resistance test was carried out by subjecting the concrete specimens to temperatures between 700°C-1000°C. The gradation test on coarse and fine aggregate gave 2.18, 4 and 1, 1 coefficient of uniformity and coefficient of curvature respectively. Three forms of slump namely true, shear, and collapse, with height of 60mm, 8mm, 3mm were obtained respectively. At a 2% replacement level, the compressive strengths recorded were 6.62 N/mm² at 7 days, 10.77 N/mm² at 14 days, 11.00 N/mm² at 21 days, and 11.11 N/mm² at 28 days. Additionally, a control compressive strength of 6.93 N/mm² was recorded, while fiber-reinforced concrete (FRC) achieved a compressive strength of 8.12 N/mm² under fire resistance conditions. In conclusion, Fibre-reinforced concrete can be adopted in concrete constructions, and prepared with 2% fibre replacement at high curing periods in places prone to high thermal and fire exposure.