India’s road construction sector is experiencing a significant transformation, driven by a growing emphasis on sustainability and innovation. In recent years, the sector has seen significant advancements due to the introduction of innovative materials such as bitumen, fly ash, plastic waste and geosynthetics designed to enhance the durability, sustainability and efficiency of roads. Traditional materials such as asphalt and concrete are being supplemented or replaced by novel alternatives offering improved performance and reduced environmental impact.
The country’s infrastructure demands have led to increased production and utilisation of these materials, which are not only paving the way for more resilient infrastructure, but also addressing critical issues such as resource scarcity and carbon emission reduction.
Key initiatives
The future of road construction is set to be revolutionised by a convergence of innovative materials and sustainable practices. In line with this, the Development Council for Cement Industry is leading efforts to enhance industry performance, eliminate waste and standardise products, thereby ensuring a sustainable future for infrastructure. Further, JSW Cement’s pioneering use of slag in green cement production has set a precedent, earning it the first GreenPro Certification for Portland Slag Cement in India.
The National Highways Authority of India (NHAI) plans to introduce a revolutionary technology for road maintenance in the country. This technology will enable roads to “repair” themselves using a new type of asphalt. This material, infused with steel fibre and bitumen, will automatically spread to cover gaps and, along with steel threads, fill potholes.
The introduction of materials such as warm mix asphalt, geosynthetics, glass fibre-reinforced polymer, ground granulated blast furnace slag and bio-based binders is gaining momentum, promising to make road construction more environmentally friendly. Eco-friendly geopolymer concrete, offering a sustainable alternative to conventional Portland cement concrete, stands out in this green revolution. Materials such as glass, fibre and steel should be prioritised, especially in coastal areas where rusting is a significant concern.
In a recent development, a Mumbai-based tyre recycling company has taken the initiative to grind up tyre waste to produce a material used to reinforce asphalt in road construction. Over the past decade, it has recycled 6 million used tyres for this purpose. Recycling tyres into road-building material, known as crumb rubber modified bitumen (CRMB), is highly energy-intensive due to the high temperatures required to process the rubber. However, it produces significantly lower carbon dioxide emissions compared to regular asphalt and results in more durable roads.
Plastic waste
The use of plastic waste in road construction is gaining momentum as a sustainable alternative to traditional materials. For instance, the Madhya Pradesh Rural Road Development Authority used plastic waste to build 35 km of roads across 17 districts. The acceptance of this material is now steadily increasing, driven by stringent enforcement of regulations by authorities.
As of January 2024, plastic waste, particularly single-use plastics, is being widely used in the construction and reinforcement of roads in Uttar Pradesh. This initiative has become a model for India, demonstrating that road construction can be both cost-effective and durable.
Furthermore, up until February 2024, plastic waste has been utilised in over 2,000 km of roads in Bengaluru and over 1,000 km of roads in Tamil Nadu. The National Rural Infrastructure Development Agency has constructed over 13,139 km of roads using this material. Furthermore, about 2,900 km of national highway length has been constructed using waste plastic.
Fly ash
To reduce carbon emissions and balance the high costs of cement and steel, it is essential to incorporate alternative materials such as solid waste and fly ash. To address the issue of highway projects being delayed due to the unavailability of fly ash, the government has mandated all thermal power plants within a 300 km radius of these projects to provide fly ash free of cost and with immediate effect, as of October 2023. Notably, in major projects such as the Delhi-Mumbai Highway, Delhi Ring Road and Ahmedabad-Dholera Road, 5 million tonnes of municipal waste has been used as alternative material.
The first geogrid-reinforced fly ash approach embankment was constructed for the Okhla flyover bridge in Delhi. During the construction of the Bandra-Worli sea link bridge, fly ash was mixed with concrete to make the structure durable and eco-friendly. Meanwhile, BALCO has partnered with Shree Cement Limited to supply 90,000 metric tonnes of fly ash for cement production.
One notable example of fly ash utilisation is the 135 km long, six-lane Eastern Peripheral Expressway, which incorporated 12 million cubic metres of fly ash in its construction. This demonstrates the significant role fly ash can play in the development of sustainable infrastructure.
Geosynthetics
Geosynthetic materials, such as geotextiles, geogrids, geonets and geomembranes, are becoming increasingly popular in road construction due to their versatile applications and numerous benefits. These materials are crucial for developing paved roads, as they act as separators, creating capillary gaps that mitigate frost activity in frost-prone soils. Roads are the primary users of geogrids, which are employed in various applications such as slope creation, slope rehabilitation, widening pavements, erosion control, filtration and drainage.
Several key road projects have deployed these materials, including the Koilwar-Bhojpur (II) project in Bihar, the Tileibani-Sambalpur highway in Odisha, the Biharsharif-Barbigha-Mokama road in Bihar and the Udaipur-Dungarpur-Shamlaji road in Rajasthan.
Bitumen
Bituminous binders play a crucial role in road and pavement construction by serving as the adhesive that binds stone, sand or gravel in asphalt mixtures, resulting in durable and flexible surfaces. The Ministry of Road Transport and Highways (MoRTH) has updated its guidelines to cater to various mixes tailored to specific traffic loads and different climatic zones.
These guidelines consider factors such as ambient temperature, rainfall, snowfall and traffic intensity across India, applicable to all new projects currently open for bidding. Moreover, the quality of highways will be evaluated during the re-laying of existing roads. Meanwhile, Praj Industries’ lignin-based bio-bitumen is set to revolutionise traditional bitumen usage, providing a sustainable alternative recognised internationally for its potential in asphalt applications.
Owing to severe heatwaves in India, the use of polymer modified bitumen is being encouraged to ensure the durability of the highways. CRMB is also being advocated for road construction. The material has previously been used in the Purvanchal expressway, successfully reducing 3,200 metric tonnes of CO2 emissions.
Future targets and outlook
India is set to ensure innovation and sustainability in the road sector, with targets such as tripling its domestic steel production capacity by 2047, alongside initiatives such as the National Green Hydrogen Mission and the Steel Scrap Recycling Policy, which aim to decarbonise the sector and significantly reduce emissions.
Achievements such as PNC Infratech Limited’s record-breaking bituminous mix laying and the NHAI Guinness World Record for the longest continuously laid bituminous lane highlight advancements in road construction techniques. Innovative technologies such as CRMB are enhancing the durability and quality of road surfaces while promoting environmental sustainability. MoRTH is also advocating for the use of treated wastewater in road construction and incentivising the use of construction machinery powered by alternative fuels.
Going forward, the adoption of local and marginal materials, utilisation of industrial by-products such as slag, recycling of materials and employment of better mix design practices are some of the strategies being explored for road construction. Cold mix technology, the use of warm mix additives, pavement recycling, full-depth reclamation and the use of processed steel slag aggregates are some of the technologies leading the way towards sustainability in highway construction.
As these developments converge, the future of road construction in India looks promising, with a strong emphasis on sustainability, innovation and efficiency, paving the way for a greener and more resilient infrastructure network.
