Treated jute geotextiles manufactured from a process developed by IIT Kharagpur, which is yet to be commercialised, could be a sustainable solution to the problem of erosion.
In the modern construction world, the use of biomaterials is growing. These materials have reduced energy costs and acted as carbon sinks.
One such material is the bust fibre derived from jute. The commercial use of jute-based geotextile has been pervasive in preventing soil loss from embankments and exposed natural or cut slopes and instigating germination and vegetation growth on the slope face to prevent shallow mechanical instabilities. Jute textiles have also been used to cover plants to protect them against frost.
And the National Jute Board has been encouraging the use of geotextile for road construction for the past several years.
Jute geotextiles are natural variants of synthetic geotextiles based on manmade polymers. The purposes of geotextiles in erosion control are to prevent loss of soil particles from the exposed surface of the slope, dissipate splashing energy, and prevent the development of excessive water pressure and exit velocity by draining off water across and along the slope face efficiently. These, in turn, help consolidate the soil without extraneous mechanical intervention.
Despite these advantages, geotextiles based on natural fibres like jute, find limited use in engineering projects because of their susceptibility to biological, chemical and physical degradation. Several chemical treatments, based largely on coating and blending strategies, have been developed to improve the resistance of natural fibres to moisture and biodegradation. However, the processes are often complex and energy-intensive, and products are expensive and potentially toxic.
Researchers at IIT Kharagpur attempted to take on the challenge of developing a chemical or biological process to make jute and other lignocellulosic fibres less hydrophilic and more degradation resistant largely using eco-friendly reagents without compromising on the ductility and flexibility of the fibres. They have developed processes to address this bottleneck by using inexpensive and eco-friendly reagents and processes. They manufactured geotextiles from chemically or biologically modified jute fibres and evaluated their durability and strength in the laboratory and small-scale field applications.
Laboratory testing has exhibited improved resistance of jute fibres and fabric against biological, chemical, UV and moisture-related degradation. Improved characteristics of chemically or biologically modified jute fibres, yarns or fabric were found to be owing to the alteration of fibre chemistry and development of a hydrophobic and degradation-resistant, cross-linked, non-leachable resin coating on the fibre surface.
Chemical treatment of jute fibres exhibited 75 per cent increase in tensile strength. Similarly, water absorption and equilibrium moisture content were reduced remarkably for yarns spun from treated fibres. To test biodegradation resistance, the samples were found to retain 60-62 per cent of their initial tensile strength after a 90-day soil burial test in comparison to only 12 per cent for untreated fibre. A salinity-related degradation test showed the treated samples to retain 61-74 per cent of their initial tensile strength. On degradation tests under extreme acidic and alkaline conditions, treated samples retained as much as 60-80 per cent of their initial tensile strength.
Laboratory study and field experience also show a manifold increase in the longevity of the jute geotextiles that underwent the chemical treatment compared to their untreated counterparts. The cost of treatment was found to be about Rs 17 to Rs 19 per sq m of 700 g per sq m woven jute fabric. These figures are remarkably lower than the costs of alternative treatments currently under use.
Demand of geotextiles in erosion control is likely to rise as engineering efforts focus on strengthening river training dikes in India and abroad. Treated jute geotextiles manufactured from the process developed by the IIT Kharagpur team could be a sustainable and eco-friendly solution to the problem. The team is now looking forward to collaborators to assist in the commercial application of treated jute geotextiles in the construction industry.
Meet the researchers
As lead researcher Prof Debasis Roy points out, ´Chemically or biologically modified natural polymers are just baby steps in an effort towards sustainability in erosion control interventions.´ Being interdisciplinary in nature, the project also involves Prof Ramkrishna Sen from the Department of Biotechnology and Prof Basudam Adhikari from the Materials Science Centre. While Prof Adhikari conducted the research on development of jute geotextiles and a suitable processing technique for rubber coating of jute, Prof Sen refined the microbial treatment segment required to develop the jute geotextiles with sustainable bioprocess integration and optimisation.
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