Bitumen, a black, viscous material derived from crude oil, is commonly used as a binder in road construction. Lignin, however, is a natural polymer found in plant cell walls and is abundant in agricultural waste.

Processing lignin into bio-bitumen offers an environmentally friendly solution, reducing greenhouse gas emissions by up to 70 per cent compared to conventional bitumen.

In addition to bio-bitumen, the mixture also contains 10 per cent rubber powder, further reducing the proportion of petroleum bitumen used. India imports 50 per cent of its bitumen requirements, costing Rs 250–300 billion annually. For this project, which features up to 15 per cent bio-bitumen blending, savings of Rs 40–45 billion in foreign exchange have been estimated. To meet the 15 per cent blending target, around 15 lakh tonne of bio-bitumen would be needed.

The viability of lignin-based bio-bitumen was first tested on a service road in Halol, Gujarat. After two and a half years and three monsoon seasons, the CSIR-CRRI confirmed its durability with no signs of distress. The Nagpur-Mansar highway could serve as a demonstration of how scalable this technology is for larger projects.

The success of this project will be assessed over the next two years as the CRRI evaluates the road’s performance under heavy traffic and varying weather conditions. A CRRI scientist mentioned that the bio-bitumen will pass the endurance test if the road’s deflection remains within 0.4mm during this period.

Union Minister Nitin Gadkari stated that CRRI would submit a detailed report on the results based on blending performance. Once the report is finalized, bitumen manufacturers will be directed to develop a policy for sourcing lignin for blending purposes. He also mentioned that 40-grade bio-bitumen, known to be stronger than its conventional counterpart, has already been developed.

Gadkari emphasised that this marks the beginning of sourcing raw materials for bitumen from farmers, which aligns with the broader goal of fostering sustainable infrastructure.

While inaugurating the project, Union Minister Nitin Gadkari highlighted the dual economic and environmental benefits. He mentioned that the bio-bitumen used in the project would reduce dependency on imports and transform agricultural waste into a valuable resource. He added that farmers would evolve into not just food producers but also energy providers.

India’s bitumen consumption is expected to grow from 88 lakh tonnes in FY24 to 100 lakh tonnes in FY25. This innovation aligns with the Aatmanirbhar Bharat mission by reducing import dependency and boosting domestic production, according to the company.