With a growing population and developing economy, India is currently witnessing tremendous large-scale infrastructure development. As a result of investments in sectors such as railways, roads, power, and water and sanitation, the market for geosynthetics is also growing. Geosynthetics are synthetic materials made from polymeric or natural substances in the form of a sheet, a strip or a three-dimensional structure. These materials can be utilised to make projects more environmentally friendly since they are easy to produce and ship. They perform five primary functions – separation, reinforcement, filtration, drainage and containment. Geosynthetics are classified based on physical attributes and manufacturing procedures. The categories are geotextiles, geomembranes, geogrids, geonets, geosynthetic clay liners, geofoam geowells, geopipes and geocomposites.
Indian Infrastructure takes a look at the applications of geosynthetic materials across infrastructure sectors…
Roads and bridges
Geosynthetics are a top choice for developing long-lasting and sustainable highway infrastructure. With the growing development of roads across the country, the use of geosynthetics is also increasing. These are used particularly to fill gaps between roads and improve the soil structure. The most commonly used geosynthetic products in the construction of roadway systems include woven and non-woven geotextiles, and geogrids (biaxial and multiaxial). Geotextiles are being used in the construction of roads and bridges. They help ensure quick and quality construction of roads, thereby increasing the life of pavements by 30-50 years. In addition, geocells, geonets or geo-composite drainage products and geomembranes are also used for various purposes.
The Ministry of Road Transport and Highways is conducting multiple studies related to geosynthetics, geogrids, geonets and natural fibres in collaboration with the IIT Hyderabad and IIT Chennai.
Conventional construction materials have a high carbon footprint, which poses a significant environmental concern. In contrast, geosynthetics are built for durability and sustainability, resulting in a significantly lower carbon footprint. The use of geosynthetics not only reduces the overall cost of a project but also the need for natural aggregates. These man-made materials play a crucial role in the migration of reflective cracking in asphalt overlays, separation, stabilisation of road bases, stabilisation of road soft subgrades, and lateral drainage.
Geosynthetics offer various functionalities that make them ideal for various applications related to railway embankments including construction of new embankments with fine-grained soils, ground improvement in case of soft sub-soils, reduction in the thickness of the blanket layer, etc.
The most commonly used geosynthetics in the railway sector are geotextiles, geogrids, geonets, geomembranes, geocomposites and geocells. Geotextiles coupled with geogrids provide stabilisation and reinforcement to tracks. Geotextiles are being used in railway tracks on the Imphal-Jiribam line in Manipur. The north-eastern states, especially Manipur, are prone to heavy rainfall throughout the year leading to flooding, landslides and soil erosion. Thus, the use of geotextiles is being increased to avoid such situations. Further, geosynthetics can be utilised for rehabilitation and strengthening of existing weak formations in the railway sector. These materials are also being used for waterproofing and drainage and reinforced steep slopes.
Further, geosynthetics are being used where heavy axle loads and high speeds are in operation. Dedicated freight corridors and high speed rail corridors, which entail heavy axle loads, are being implemented in the country, further driving the use of geosynthetics in the construction of railway tracks.
With air traffic increasing over the years, there is a need for better engineering, increased capacity and enhanced safety measures. With this, the use of geosynthetics is also increasing in the sector. Geosynthetics are largely used in the construction and extension of runways as well as in reinforcing pavements in the airport sector.
In July 2022, the trial landings on the first airstrip in Idukki district of Sathram, Kerala, were unsuccessful because a portion of the airstrip was washed away in a landslip following heavy rain. After assessing the entire situation, the State Disaster Management Authority team recommended a geotextile fixing on the caved-in portions to ensure the safety of the runway.
In another development, the Kolkata airport runway faced problems of rainfall drainage during the monsoon season, which posed a risk to the pavement due to the erosive effect of water flowing underneath it. To address these issues, a non-woven geotextile called Geodren was used on the runway. Geodren was able to serve three functions – separation, filtration and drainage. To achieve superior permeability performance on the geotextile surface, a blend of fibres of a specific linear density was also used, resulting in a considerable increase in drainage capacity. In addition, the thicker fibres ensured improved durability in terms of both chemical ageing and microbiological resistance.
Geosynthetics are highly valuable in the tunnel sector, with extensive use in tunnel engineering, including two major applications – waterproofing and drainage. Geomembranes are used as liners in hydraulic tunnels. Hydraulic tunnels that transfer water are lined with different materials such as steel and shotcrete to provide structural stability and prevent water leakage. Geomembranes ensure minimal liner deterioration in such cases. Geotextiles and geomembranes have low permeability, which makes them ideal for waterproofing. They are resilient to rotting, swelling, ageing, puncture and chemicals, and they can withstand adverse weather conditions. Geomembranes are thin, so they do not compromise the tunnel diameter, eliminating the need for cross-sectional area reduction. Moreover, they can be used for repairing old tunnels. Overall, they are important components in the construction of tunnels, significantly improving the structural integrity and long-term performance of the projects.
In a recent development, the GMR Group started repairing the headrace tunnel of its 188 MW Bajoli-Holi hydropower project in Chamba district, Himachal Pradesh. The GMR Group has appointed a Swiss company to install a geomembrane in the tunnel to block the seepage from the it, since this is affecting the entire village of Jharauta.
Water and wastewater treatment
Geosynthetics are being effectively employed across a wide range of applications to improve the process of storing and treating water and wastewater. These materials are being used because of properties such as cost-effectiveness, ease of installation and increased efficiency. In addition, geosynthetics are environmentally friendly. The growing use of geomembranes in wastewater management due to their exceptional chemical resistance is driving market growth.
The way forward
Geosynthetics provide cost savings, extend the lifespan of infrastructure projects and, most importantly, cause less environmental harm. Today, the benefits of geosynthetics are increasingly being recognised. However, their adoption in the infrastructure sectors has not yet taken off, and their promise is still largely unrealised. It is necessary for players in the infrastructure sector to make use of geosynthetics more frequently. While the government promotes the use of geosynthetics, much more needs to be done to increase their deployment. The need of the hour is to carry out necessary research and development for the use of geosynthetics in infrastructure sectors, particularly for specific use cases.
The geosynthetics market in India is expected to grow significantly due to the ongoing infrastructure development. The road sector is expected to be a key driver of growth for the geosynthetics industry. The railway sector is also rapidly developing and is expected to increase the demand for geosynthetics due to the upcoming dedicated freight corridors and high speed train projects.