Construction activity in the infrastructure sector has been increasing significantly over the past few years. With the fast-paced development and commencement of new projects, there has been an increase in the adoption of new and advanced technologies aimed at increasing the lifespan of projects and improving their quality. As such, geosynthetic products too have been seeing increased adoption in the infrastructure sector.
The use of geosynthetics in infrastructure projects is aimed at improving their quality and extending their lifespans. Civil engineering projects face challenges during the construction process, and geosynthetics provide a cost-effective and long-term solution to the various problems. The different types of geosynthetics include geotextiles, geogrids, geocells, geomembranes, geomats and geocomposites. These are known to provide a wide range of functions, including separation, drainage, erosion control and filtration. They are also used for soil stabilisation, reinforcements, etc. The use of geosynthetic materials helps in preventing landslides and erosions, and stabilising embankments. Further, they provide environmental benefits such as conservation of natural resources. Given these advantages, geosynthetics have a wide range of applications in roads, tunnels, railway track beds, drainage systems, ports, airports, etc.
Roads
Road construction requires materials of high quality to strengthen the soil and build long-lasting structures. Geosynthetics are known to aid in the strengthening of the weak soil strata over which construction takes place. Further, geotextiles in particular are used to reinforce the soil and protect it from damage and erosion, while also allowing water to drain off. They are also used for providing stability during the construction of roads in difficult terrain such as mountains. With the aim of increasing the adoption of geosynthetics, the Ministry of Road Transport and Highways has promoted its use in road construction. Further, the Indian Road Congress has put forth various standards and guidelines for the use of geosynthetics in the construction of highways.
Geosynthetics have wide-ranging applications that are being used across the country. For example, the rural road stretch connecting Bettadapura village in Karnataka bore damages such as unevenness and major settlement cracks. Depression and distress signs had also been noted. The damage could be attributed to the fact that the road passes through rich black cotton soil, which has a low bearing capacity; as well as the continuous seepage of water through the crust of the road due to the presence of agricultural fields on both sides. Geocells filled with granular material were used for its rehabilitation and to stabilise the pavement. This helped in increasing soil strength and load capacity, enhancing drainage, etc.
Geocells were also used for erosion control on the road embankments of the Ahmedabad-Vadodara Expressway in Gujarat. The embankments were protected with geocells and were filled with vegetative soil. This creates a green surface that protects against erosion, in addition to its aesthetic benefits. Geocells with concrete fillings were also used over non-woven geotextile for the construction of a drainage system, with the aim of improving down-slope stability against high water flow. Other projects that witnessed the use of geosynthetics include the Mumbai-Vadodara Expressway, and highways at Visakhapatnam, Tuticorin and Vallarpadam in Kochi.
Airports
Geosynthetics are also used in airport construction and expansion, given the need for long-lasting, high quality infrastructure. They are used for the construction and strengthening of runways, and for other engineering design challenges. For example, the Kolkata airport runway expansion project made use of a non-woven geotextile. The runway had been facing the problem of insufficient rainfall drainage, which posed risks, and there was a need to minimise the erosive effect of the water flowing under the pavement. The use of geotextiles enabled separation, filtration and drainage. Further, the installation of drainpipes increased drainage capacity. Geosynthetics were also used at Sikkim airport, which is known to be one of the world’s largest geosynthetic megastructure projects. There was a need to prevent erosion caused by slopes and the challenging terrain. Geogrids were used for stabilisation and filled with gabion stones. Geosynthetics were also used in the Cochin International Airport.
Tunnels
There is a need for tunnels to be water proofed and protected from water that penetrates through rocks. The use of geosynthetics such as non-woven geotextiles and geomembranes can help in protecting tunnels from damage. For example, the Delhi Metro Rail Corporation has employed geosynthetics in its tunnel works. Geotextiles have been used for protection, separation and drainage between the shotcrete lining at the top and the geomembrane sheet. Geotextiles have also been used in the Atal Tunnel. Various other tunnel construction projects have made use of geosynthetics.
Railways
Geosynthetics are very useful in railway construction and the laying of railway tracks. They are proven to have the ability to tackle issues such as drainage, reinforcements and erosion. Geotextiles aid in the construction of tracks where the soil is weak through the use of reinforcements, and in other functions such as stabilisation of the ballast layers.
For example, geosynthetics were used for ballast stabilisation in Shivpuri, Madhya Pradesh. The railway structures there had been experiencing quick deformation due to the concentration of load at the same position and the deformation of soft soil. Other problems also existed, such as reduction of frictional properties due to the movement of fines from the subgrade into the ballast. Geogrids and geotextiles were used to increase efficiency, leading to separation, filtration and reinforcement. This further enabled the draining of the water that entered the geosynthetics from above.
Geosynthetics were also used in the construction of the railway line from Tripura to Sabroom, where there was a need for stabilising the track beds. A woven multifilament geotextile and a biaxial geogrid were used for separation and filtration between the blanket and the subgrade material.
Other sectors
Geosynthetics also have wide applications in the port sector. They are used for soil stabilisation and to increase load-bearing capacity. They are also used in the construction of bridges and landfills, as well as for riverbank protection and as barriers for erosion control. Further, they are used in landscaping projects.
Moreover, there has been an increase in the uptake and use of coir and jute geotextiles. For example, coir geotextiles have been employed for the construction of rural roads under Pradhan Mantri Gram Sadak Yojana-III.
Challenges and way ahead
Although the use of the geosynthetics has been increasing over the years, adoption is still not at the expected level. There are many challenges that still remain with respect to the application of geosynthetics in the infrastructure sector, both in India and globally. Geosynthetics can sometimes underperform due to their varied applications, or environmental conditions such as extreme temperatures. Further, challenges such as unavailability of skilled labour and loss of efficiency due to improper implementation could also be potential setbacks.
Looking forward, geosynthetics have huge potential in the infrastructure sector, given their benefits and the learnings gleaned from successful projects. Their high durability and ability to increase productivity and enable long-term cost reduction could be driving factors for their increased uptake. This potential is buoyed by the large number of infrastructure projects in the pipeline. Further, the use of geosynthetics such as coir and jute geotextiles has environmental advantages.