Natural fibres as sustainable engineering materials: scope, challenges, and prospects

Abstract

Natural fibres are increasingly becoming popular in various geotechnical applications. Being environment-friendly renders them a more appealing choice over the polymer-based counterparts. However, the strength and deformation properties and the long service life of synthetic polymer fibres cannot be matched by natural fibres. Natural fibres and geotextiles have been found to lose strength over time while in use. Among the tropical fibres, coir has better longevity due to its high lignin content. In-field studies presented in available literature conclude that the tensile strength of coir geotextiles drops by around 80% of its actual strength within the initial year of its installation in a tropical climate, whereas the strength loss for jute geotextiles takes place at an even faster rate. Investigations on the durability enhancement of natural fibres for composites have been reported worldwide. Most of the chemicals used for surface modification are considered expensive, hazardous and unsuitable for geotechnical applications. Moreover, certain types of modifications alter the desirable properties such as drapability, flexibility and fibre strength, which are the crucial characteristics for geotextiles. A critical review of the fibre modification methods attempted to date has been presented. The effectiveness of plant-based natural components on the surface modification of natural fibres and the challenges that may arise are also reviewed. Despite the research reported in the past, it remains necessary to pursue further investigations until natural fibres/geotextiles with suitable environment-friendly treatments emerge as viable and sustainable alternatives to synthetic geosynthetics. Given their cost-effectiveness, local availability, and reduced carbon footprint, natural fibres/geotextiles with an extended useful life can serve as superior alternatives to synthetic geotextiles for long-term engineering applications.