New Delhi: India’s rapidly expanding road network—over 6.6 million kilometres, second only to the US—is now embracing innovative ways to reduce environmental impact by converting waste into construction materials. With national highways growing at a projected 40 km per day, and district and rural roads also increasing, the focus is shifting toward sustainable, low-carbon infrastructure.

Industrial Waste: Steel Slag Roads

In Raigarh, Chhattisgarh, a two-kilometre, six-lane road leading to the Jindal Steel Plant is being rebuilt using steel slag, a by-product of steelmaking. Earlier pilots in Hazira and Mundra ports showed that steel slag could replace natural aggregates in all pavement layers, cutting aggregate extraction by nearly 40% and reducing carbon emissions by about 30%. Over 22 million tonnes of slag generated annually are now diverted from landfills into productive use.

“Processed steel slag aggregates can substitute 100% of natural aggregates in bituminous and concrete pavement,” said Satish Pandey, CSIR–CRRI.

Countries like Japan and the Netherlands have already standardised steel slag use across road layers, showcasing how industrial waste can become a crucial resource.

Plastic Roads: Durable and Sustainable

Another innovation is geocells—honeycomb-shaped grids made from recycled plastics that, when filled with soil or aggregates, improve load distribution and strengthen roads. CRRI and BPCL have patented the system, testing it on a 1,280-square-metre stretch near the DND–Faridabad–KMP Expressway. About 20–25 tonnes of mixed waste plastic were used, demonstrating practicality even without segregation. Geocells have since been deployed in Leh and Lahaul–Spiti, where conventional materials are scarce.

India has also been incorporating shredded plastic into bitumen for nearly two decades. Adding 1.5–2% of shredded plastic increases flexibility, waterproofing, and crack resistance while diverting waste from landfills.

Agricultural Residues: Bio-Bitumen

Crop residues like paddy straw are being processed into bio-bitumen, replacing up to 30% of petroleum bitumen. This reduces carbon emissions, cuts import dependence, and addresses stubble burning, aligning with circular economy goals.

Private Sector and Green Shifts

Private players are increasingly adopting greener materials. Vertis Infrastructure Trust reused 700 tonnes of waste plastic in highway projects in Udupi and Ulundurpet, improving durability while reducing maintenance. Moglix has set up a greenfield facility in Mathura producing crumb rubber–modified and plastic waste–modified bitumen with 6,000 MT monthly capacity each.

Standardisation and Sustainability Frameworks

Experts stress codification to scale sustainable practices. CRRI and the Indian Roads Congress (IRC) are developing a Green Rating Framework for road construction materials, evaluating recyclability, embodied energy, and life-cycle impact.

The GRIHA Council, which rates buildings for environmental performance, launched an Infrastructure Rating for Highways in December 2024, covering 12 sustainability criteria like governance, carbon emissions, waste management, and social impact. NHAI’s sustainability report noted a reduction in greenhouse gas intensity and use of over 631 lakh metric tons of recycled materials, including fly ash, plastic waste, and reclaimed asphalt.

“Integrating sustainability models into highways can embed circularity and carbon reduction goals, supporting India’s 2070 net-zero commitment,” said Sanjay Seth, Vice President and CEO, GRIHA Council.

India’s push toward ‘waste-to-worth’ roads is not just about infrastructure—it is an emerging model for climate-conscious development, demonstrating how industrial, municipal, and agricultural waste can transform the nation’s highways into sustainable arteries for the future.