Sustainable road and bridge construction practices have emerged as a cornerstone of modern infrastructure development in India, reflecting a growing commitment to balancing rapid development with environmental responsibility. Roads and bridges are critical links of trade, mobility and socio-economic development, but their traditional dependence on resource-intensive materials such as cement and steel has long carried a substantial environmental cost. The road sector alone is estimated to account for roughly 40 per cent of pollution in the country, highlighting the urgency for cleaner, greener and more resilient alternative approaches.
To tackle this, circular economy principles, such as the reuse of industrial by-products, municipal waste and plastic waste, are increasingly being integrated into large-scale road and bridge projects. Simultaneously, modular and precast construction systems are gaining prominence for their ability to reduce emissions, and improve road construction quality. Complementing these advancements, major research institutions, including the Council of Scientific and Industrial Research and the Central Road Research Institute (CSIR-CRRI), and the Indian Institutes of Technology (IITs), are driving breakthrough research and development (R&D) innovations to accelerate sustainable engineering solutions.
Using waste as alternative construction material
Industrial by-products
The increased focus on sustainable road construction is accelerating the use of industrial by-products as substitutes for traditional materials. This allows turning waste into valuable construction materials that cut emissions and reduce reliance on virgin resources. Among industrial by-products, fly ash is now being widely reused in road construction. According to the National Thermal Power Corporation, of the approximate 340 million tonnes (mt) of fly ash produced in 2024-25, around 32 per cent was utilised in the construction of roads and flyovers. This growing utilisation reflects a clear shift from waste disposal to resource optimisation. Other than this, the usage of steel slag and blast furnace slag, by-products of the steel industry, has been picking up pace. Roads built with these processed aggregates are estimated to be about 40 per cent more cost-effective and nearly three times more durable than conventional bituminous pavements. To effectively reap these advantages, the use of steel and blast furnace slag is being explored as pilot projects. For instance, eco-friendly ground-granulated blast furnace slag is being deployed in the expansion of the 76 km National Highway (NH)-53 stretch between Chandikhol and Paradip in Odisha. The blast furnace slag was supplied by Tata Steel’s Industrial By-product Management Division. Besides, ArcelorMittal Nippon Steel India secured a technology licence from CSIR-CRRI in July 2025 to convert steel slag into engineered road aggregates. Going forward, the adoption of steel slag is expected to increase further in the upcoming road projects across the country.
Composite materials using these industrial by-products also offer practical and sustainable solutions. In line with this, the Andhra Pradesh Government launched a pilot project in August 2025 to deploy Ecofix, a composite made from steel slag and tar, for pothole repairs. The material offers an eco-friendly and ready-to-apply solution that requires no heating and can be used even during the rainy season. In July 2025, the Adani Ports and Special Economic Zone, inaugurated a 1.1-km steel slag road at Hazira port. Designed with a flexible pavement structure by CSIR-CRRI, the road connects the multipurpose berth to the coal yard. It showcases a higher load-bearing capacity, a longer service life and lower construction costs.
Municipal waste
The integration of municipal waste into road construction is emerging as a vital driver to address both waste management pressures as well as the need for resource-efficient building materials. In October 2024, the Ministry of Road Transport and Highways (MoRTH) issued guidelines to promote the use of urban solid waste and inert materials in NH construction, aiming for more sustainable practices.
Building on these circular economy principles, about 8 mt of legacy municipal waste has been used for road construction in Delhi and Ahmedabad, as of November 2025. The approach is being scaled up, with segregated municipal solid waste planned for use in the construction of the upcoming six-lane, 110 km Capital Region Ring Road project in Bhubaneswar, Odisha. In fact, the Odisha Government is also exploring the use of shredded plastic blended with bitumen and aggregates. On similar lines, around 690 tonnes of single-use plastic has been deployed in Uttar Pradesh to renovate about 606 km of roads, as of July 2025. By recycling 1,400 mt of plastic waste under the Pradhan Mantri Gram Sadak Yojana (PMGSY) III, the state has saved over 9 million tonnes of stone aggregates and cut diesel use by 700,000 litres, lowering construction costs by roughly 15 per cent while substantially reducing the carbon footprint.
In addition, plastic-mixed bitumen is being explored for road construction and repair purposes. Experimental pilot projects were undertaken to deploy plastic-mixed bitumen for road repair and maintenance around the Salt Lake area of Kolkata, West Bengal, in June 2025 by the Bidhannagar Municipal Corporation. Furthermore, similar trials undertaken by the Hubballi-Dharwad Municipal Corporation in May 2025, demonstrate that blending about 8 per cent shredded plastic with bitumen enhances pavement strength, improves water resistance and lowers material costs. With savings of roughly Rs 150,000 per km compared to conventional asphalt, these initiatives highlight a growing municipal-level shift towards waste-valorised road building.
Uptake of precast and modular construction
India’s road sector is rapidly shifting towards prefabricated and modular construction, driven by the need for speed, cost efficiency and sustainability. Precast elements manufactured off-site reduce on-site disruption, material waste and emissions while improving overall construction quality. While precast construction has long been prominent in bridge works, it is now being extended to NH works. Projects costing over Rs 3 billion are mandated by the central government to use precast components such as concrete slabs to enhance construction speed, quality and efficiency. Initially applied to non-critical elements such as box culverts, storm water drains and footpaths, the approach is already visible in major projects. In Goa, the Rs 3.64 billion Porvorim elevated highway corridor is using around 1,430 precast segments. Meanwhile, under the six-lane Pune-Bengaluru NH-48 (Satara-Kagal stretch) project, around 1,223 heavy precast segments have been installed over a 3.5 km span, as of September 2025. The segments, each weighing 125-135 tonnes, are fitted on 93 single pillars along Karad city.
Innovative practices for asphalt road construction
Across India, a new wave of innovation is reshaping road and bridge construction. Several innovative approaches are being adopted across road construction involving asphalt and related aggregates. Aligning with this, the Public Works Department of Goa is planning to mandate the use of batch-type hot mix plants for all pothole-filling and road-laying works costing over Rs 10 million. These plants ensure precise screening and weighing of raw materials, producing a uniform, well-graded asphalt mix that improves durability and overall pavement quality. Complementing this shift towards high-performance materials, in June 2025, the Bruhat Bengaluru Mahanagara Palike piloted stone matrix asphalt (SMA) for flyover repairs. SMA offers superior resistance to rutting, cracking and water damage, significantly extending pavement life and reducing the frequency of maintenance.
R&D for boosting indigenous construction techniques
Enhanced R&D traction in India’s road construction is improving long-term asset performance. CSIR-CRRI has been actively involved in R&D for sustainable road construction, focusing on solutions that reduce recurrent road damage, lower maintenance costs and integrate climate-resilient materials. As of August 2025, the institute has developed several advanced technologies and materials, including modified mix seal surfacing (MSS+) technology, which eliminates the need to heat aggregates and bitumen, enabling all-weather, energy-efficient construction. Roads built using MSS+ have shown superior performance compared to conventional hot-mix pavements. Reflecting on the growing adoption of MSS+, the Uttar Pradesh Rural Road Development Authority has planned to deploy this technology to construct 202 km of 30 mm roads under the PMGSY in 2025.
Premier research institutions such as the IITs are also developing sustainable road construction materials. For instance, in July 2025, IIT Indore developed a cement-free geopolymer concrete using fly ash and granulated blast furnace slag. It eliminates the need for water curing and cuts carbon dioxide emissions by up to 80 per cent. Its rapid-setting properties make it well suited for time-sensitive projects such as bridges. Meanwhile, IIT Jodhpur is developing rain- and flood-resilient pavements with improved drainage, supported by technologies such as recycled concrete aggregates from demolition waste, plastic-infused paver blocks and durable cold-mix asphalt for greener highways.
Navigating future pathways
The next phase of sustainable road and bridge development in India hinges on effectively aligning policy, institutional capacity, and financing. In this context, the Gati Shakti programme aims to deploy robust tools, such as national green rating frameworks and carbon-footprint monitoring systems, to lay the groundwork for measurable and standards-driven sustainability. A major shift is underway as the MoRTH plans to mandate that 70-80 per cent of precast concrete elements be utilised in construction. This transition, driven by factory-controlled quality, uniformity, and faster construction, positions precast technology as a cornerstone of India’s low-emission, high-durability road ecosystem. Further, in difficult terrains, the recommended use of geosynthetics by CRRI provides durable and resource-efficient solutions for terrain stabilisation and drainage enhancement.
Moreover, innovative initiatives, such as the government of Maharashtra’s pioneering debris-recycling initiative in Nagpur, further strengthens circular-economy models by converting construction waste into aggregates for rural roads, easing pressure on natural resources and landfills.
In order to achieve comprehensive progress, a clean-energy transition must accompany construction reforms. Going forward, the expansion of solar corridors and electric highways (e-highways), along with the use of electric construction equipment, will be paramount for fostering sustainable operations. The plan to upgrade 23 NHs, spanning a length of 5,500 km, to e-highways by 2027 under the National Highway for Electric Vehicles programme signifies a systemic shift towards low-carbon mobility infrastructure. These e-highways will feature electric vehicle charging infrastructure every 50 km. The transition is also reflected in the deployment of electric-powered construction equipment in projects such as the Amritsar–Jamnagar Expressway. Ultimately, a shift from cost-based to lifecycle-based road network planning, along with the incorporation of sustainability metrics at every stage of project development, will be central to building a resilient and carbon neutral road infrastructure.
Aditi Gupta
