From smog to streets: How crop waste blamed for Delhi’s pollution could soon build roads

What if the crop waste that chokes Delhi every winter could quietly turn into smoother roads? Scientists at CSIR-Central Road Research Institute (CRRI) say it already can. A new bio-bitumen technology that converts rice straw and other farm residue into road-building material moved a step closer to real-world use on Wednesday, when it was officially transferred to 14 companies in the presence of Union road transport and highways minister Nitin Gadkari, a TOI report stated. The move signals strong industry interest in a solution that tackles air pollution and rising infrastructure costs at the same time.

A historic shift from residue to roads

Calling it a first-of-its-kind achievement, Gadkari said India has taken the global lead in commercial bio-bitumen production.

"Today marks a historic milestone, as India becomes the first country in the world to commercially produce bio-bitumen. The technology is excellent and has huge potential. I recommend using as much farm waste as possible and utilising it to its full capacity. Once it gets BIS certification, I can guide collaboration with the IRC," said Gadkari at CSIR’s Technology Transfer Ceremony, titled “From Farm Residue to Road: Bio-Bitumen via Pyrolysis”. Union minister Jitendra Singh was also present.


CRRI scientists say roads built with bio-bitumen match, and sometimes outperform, conventional bitumen roads. They resist cracks, potholes and even Delhi’s intense summer heat.

When pollution became the problem to solve

The idea took shape in 2021, when CRRI scientists G Bharath and Ambika Behl asked a simple but bold question: could Delhi’s pollution problem itself become part of the solution? They zeroed in on stubble burning, one of the biggest reasons behind the capital’s winter smog, and began experimenting with agricultural waste.

Working with CSIR-Indian Institute of Petroleum, the team spent three years refining the process. Their effort paid off in 2024, when the first trial road using bio-bitumen came up in Meghalaya.

"This stretch has faced two monsoons and still maintains highway quality," an official aware of the project said.

How farm waste turns into road material

The process avoids fire altogether. Instead of burning rice straw, it is collected from farms, compressed into pellets and heated in a low-oxygen environment. This releases bio-oil, which is then blended with conventional bitumen, partly replacing petroleum-based material.

The final mix behaves like regular bitumen, making it suitable for long-lasting road construction without major changes to existing methods.

Big savings, cleaner air

Gadkari said the benefits go beyond roads. Using agro-waste reduces pollution from crop burning and strengthens the circular economy.

"With just 15% blending, India can save nearly Rs 4,500 crore in foreign exchange and reduce reliance on imported crude oil," he added.

He also stressed that future research should focus on local needs and raw material availability, rather than a one-size-fits-all approach.

Delhi roads could be next

CRRI scientists plan to approach the Delhi government within the next two months to pilot bio-bitumen on key arterial roads. The aim is to turn a seasonal pollution crisis into a permanent solution.

"The beauty of this technology is that it works with the machinery we already have. You don't need to reinvent the wheel to lay a bio-bitumen road," Bharath said, adding that bio-bitumen is also cheaper than traditional bitumen.

According to him, the recent technology transfer is meant to build nationwide capacity so more companies can produce and lay bio-bitumen roads. Roads built with this mix already meet BIS standards. The team is working with the Indian Roads Congress to push for at least a 10% replacement of conventional bitumen, though the share could go up to 30%, depending on raw material availability.

If the plan works, the smoke that once darkened Delhi’s skies could soon be rolling quietly under its tyres.