Improvement of Mechanical Behaviour of Concrete Using Natural Fibres—A Review

Concrete is a high-performance construction material that requires exiguous maintenance throughout its design life. Despite being the most popular construction material, concrete is brittle and tends to develop cracks under tensile stresses. This property of concrete has often resulted in catastrophic failures resulting in the loss of life and property. Reinforcing steel bars has been used to induce ductility and enhance the load-carrying capacity of concrete, but reinforced concrete remains vulnerable to tensile cracking due to its poor crack-arresting mechanism and the risk of metal corrosion. This can be overcome by the addition of randomly distributed discrete fibres such as steel fibres, synthetic fibres, natural fibres to the composite to form Fibre Reinforced Concrete (FRC). FRC can be cost-effective, especially if the fibre is a locally sourced waste material from agricultural activities. This paper reviews the potential of natural fibres obtained from agricultural waste to improve the tensile behavior of concrete and augment its post-crack strength. This study focuses on the mechanism of crack formation/propagation, compressive strength, tensile strength, flexural strength, drying shrinkage characteristics of natural fibre-reinforced concrete (NFRC). The properties of natural fibres including the type of fibre, its dimensions, volumetric concentration, and the required pre-treatment largely influence the overall mechanical behavior of concrete. At the same time, the major drawback of using natural fibres in concrete is their susceptibility to degradation due to fibre’s capacity for water absorption. In order to minimize the fibre degradation in NFRC, studies have looked at coating or treating the fibres, and lowering the alkalinity of the cement around the fibre. However, coating of natural fibres to achieve these properties and then testing their response to degradation inside concrete seems to be lacking in the literature. Thus, this study aims to examine the various challenges associated with the use of natural fibres in concrete.