Performance Evaluation of Coconut and Polypropylene Fibre Reinforced Concrete: A Study on Workability and Strength Characteristics

Abstract

This study investigates the effects of incorporating coconut and polypropylene fibres in varying proportions (0.5% to 4.5% by weight of cement) on the workability and mechanical properties of concrete. Slump tests, compressive strength tests, and flexural strength tests were conducted to evaluate performance. The slump values remained above 100 mm for all mixes, indicating acceptable workability, although a slight reduction was observed with higher fibre content. The compressive strength of fibre-reinforced concrete improved significantly, with the highest 28-day strength of 30.19 N/mm² achieved at 3.5% fibre content. Similarly, flexural strength showed substantial improvement, peaking at 13.11 N/mm² for the same fibre dosage. The improved strength is attributed to the effective bonding between the fibres and the cement matrix, which enhances crack resistance and structural integrity. However, beyond 3.5% fibre content, a decline in strength was observed, likely due to fibre agglomeration and poor dispersion. The optimum mix was determined to be at a 0.5 water-cement ratio with 3.5% fibre addition. These findings suggest that coconut and polypropylene fibre-reinforced concrete can be a viable solution for improving the strength and durability of structural concrete elements.