Fiber Reinforced Concrete (FRC)

Abstract

A detailed experimental investigation was conducted on the use of natural fibers—bamboo fiber, coconut fiber, and human hair fiber—as reinforcing agents in concrete. The primary aim was to explore their feasibility as sustainable, cost-effective, and eco-friendly alternatives to synthetic fibers like polypropylene or steel. Natural fibers are biodegradable, readily available, and contribute to environmental protection by reducing non-biodegradable construction waste. The experimental program involved the preparation of concrete specimens with different dosages of each fiber type. Tests were conducted to evaluate key mechanical properties such as workability (slump test), compressive strength (cube test), and split tensile strength (cylinder test). Additionally, the effects of fibers on crack propagation and post-cracking behavior were observed and analyzed. The results indicated that all three natural fibers contributed positively to the enhancement of concrete performance. Bamboo fiber, owing to its high cellulose content and tensile strength, improved the bonding within the concrete matrix and delayed crack formation. Coconut fiber, known for its high lignin content and natural toughness, significantly improved impact resistance and tensile strength. Human hair fiber, a protein-based keratinous material, proved especially effective in controlling microcracks and shrinkage due to its high tensile strength and elasticity. Among the three, coconut fiber showed the most substantial increase in tensile strength, while bamboo fiber excelled in maintaining the structural integrity of concrete under compression. Human hair fiber was particularly beneficial in reducing plastic shrinkage cracks. The study also found that a fiber content of around 1% by volume provided the most balanced improvements in strength and workability without compromising the mix’s consistency. This study highlights the viability of using waste or agricultural by-products as reinforcement materials in concrete, contributing both to structural performance and sustainability goals. The incorporation of such fibers not only enhances mechanical properties but also addresses issues of solid waste disposal and reduces dependency on industrially manufactured materials. Furthermore, the use of natural fibers supports the global movement towards green construction practices and aligns with the principles of sustainable development.

Introduction

Concrete is essential in infrastructure due to its strength and availability, but it has limitations like low tensile strength and susceptibility to cracking. Traditional reinforcement methods (e.g., steel, synthetic fibers) are effective but environmentally harmful. To address these concerns, natural fibers—bamboo, coconut, and human hair—are being explored as sustainable alternatives in Fiber Reinforced Concrete (FRC).

These natural fibers offer several benefits:

• Bamboo fiber: High tensile strength, lightweight, biodegradable; improves crack resistance and flexibility.

• Coconut fiber: Durable, water-resistant, tough; suitable for dynamic loads and impact-prone areas.

• Human hair fiber: High tensile strength and elasticity; repurposes waste and enhances bonding and shrinkage resistance.

The study aims to assess the feasibility of using these fibers in rigid pavement construction to enhance mechanical performance and sustainability. Objectives include:

1. Evaluating mechanical and durability properties.

2. Comparing environmental impacts with conventional materials.

3. Proposing design guidelines.

4. Conducting field trials.

Methodology

• Materials Used: Portland-pozzolana cement (PPC), M sand, coarse aggregates, potable water, and treated natural fibers.

• Fiber Preparation:

  • Bamboo and coconut fibers are cleaned, dried, and cut to specific lengths.

  • Human hair is washed (e.g., with acetone), dried, sorted, and incorporated based on its tensile properties (approx. 380 MPa).

• Concrete Specimen Preparation: Standard cube molds (150mm), tamping, compaction, 28-day water curing, and compressive strength testing.

Findings

Natural fiber additions improved concrete’s:

• Tensile strength

• Crack resistance

• Load-bearing capacity

• Durability

These sustainable fibers also reduce environmental impact by reusing organic waste and lowering reliance on synthetic or non-renewable materials.

Conclusion

This study evaluated the compressive strength development of concrete with various natural fibers — human hair, bamboo fiber, and coconut fiber — across different grades (M20 and M30), curing ages, and material compositions. 1) Effect of Human Hair Fiber: • Compressive strength increases with the inclusion of human hair up to 3%, beyond which a slight decline is observed. • The optimum fiber content for strength enhancement in both M20 and M30 grades is 3% at 28 days: o M20: Increased from 22.60 MPa (0%) to 24.95 MPa (3%) o M30: Increased from 33.45 MPa (0%) to 37.40 MPa (3%) • Strength gain is consistent with age (7, 14, and 28 days), indicating normal hydration and effective bonding with fibers. 2) Effect of Bamboo Fiber • Unlike human hair, bamboo fiber addition shows a reduction in compressive strength as the fiber content increases. • The highest strength is recorded at 0% bamboo, and it steadily decreases at 2%, 4%, and 5% fiber content. o 28-day strength drops from 48.648 MPa (0%) to 35.564 MPa (5%) o 56-day strength drops from 54.893 MPa (0%) to 42.935 MPa (5%) • Although bamboo fibers may improve other concrete properties (e.g., ductility or crack resistance), they adversely affect compressive strength in higher percentages. 3) Effect of Coconut Fiber (Table 4.3 - CFRC Processed) • Coconut fiber concrete (CFRC) shows moderate strength improvements, particularly when superplasticizer and W/C ratios are optimized. • Specimen 2 (5% coconut fiber, 0.4% SP, 0.36 W/C) gave the best results: o 7-day strength: 24.76 MPa o 28-day strength: 40.57 MPa • Workability remained acceptable (slump: 105–110 mm), suggesting that fiber dosage and admixtures were well-balanced. • Coconut fiber presents a viable alternative to synthetic fibers when properly proportioned. A. Conclusion • Human hair proves to be the most effective among the three fibers in enhancing compressive strength, especially at 3% content. • Bamboo fiber negatively affects compressive strength when used in high quantities and is less suitable for load-bearing applications. • Coconut fiber performs moderately well, with potential for structural use when combined with proper mix design and chemical admixtures. • The optimum use of natural fibers in concrete depends significantly on type, percentage, curing time, and mix proportions. Proper optimization can lead to sustainable and high-performance concrete for modern construction needs.

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Copyright

Copyright © 2025 Mr. Amit Kumar , Mr. Shubham Singh . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.