Inauguration of Asia's first highway with bio-bitumen surface: Giant leap towards sustainable road infra

Nagpur: Union minister for road transport and highways, Nitin Gadkari, inaugurated a 1km stretch of Asia's first highway with a bio-bitumen blended surface. The trial patch begins near the ‘Kamptee 22Km' milestone on Jabalpur-Nagpur route. The project will help cut pollution from stubble burning as the source of bio-bitumen comes from easily available crop stubble, which farmers can sell instead of torching the residue.

Calling it his dream project, Gadkari hoped if the technology takes off, air pollution will be reduced dramatically. Stubble is already fetching Rs 2,500 per tonne in Punjab and Haryana, he said. As it replaces the conventional bitumen, by 15%, it is expected to reduce the cost of road building. There are projections that it can cut imports of petroleum bitumen by at least Rs 4,500 crore initially. Along with bio-bitumen, it also has 10% rubber powder content, further cutting the proportion of petroleum bitumen.

However, the project's success is still two years away. Central Road Research Institute (CRRI), a govt body, will observe whether the road withstands heavy traffic and changing seasons. The bio-bitumen will pass the endurance test, if the road does not deflect beyond 0.4mm during the period, said a CRRI scientist.

CRRI will eventually submit a report on the results on the basis of blending and then take it forward, Gadkari told reporters after the inauguration. Once the report is submitted, bitumen manufacturers will be asked to frame a policy to purchase lignin for blending. Currently, 40-grade bio-bitumen, which is stronger than the conventional product, has been made, he said. For Gadkari, it is also the first step towards achieving the goal of sourcing raw material for bitumen from farmers.

The bio-bitumen has been made by Praj Industries, a private sector industrial biotech company, in association with CRRI. The Jabalpur highway pilot project was undertaken after another experiment by Praj and CRRI on a service road at Halol in Gujarat yielded favourable results. It withstood 2.5 years and three monsoon seasons, and the results have been satisfactory. Rather, it has emerged 40% stronger compared to conventional bitumen, said the company officials.

Here is how the entire bio-bitumen cycle works. The making of ethanol out of crop stubble, as well as compressed biogas (CBG), generates lignin as a byproduct. Lignin can be used as a raw material for making bio-bitumen. The bio-bitumen is then blended into the conventional bitumen. The technology developed by Praj has enabled blending up to 15%.

Gadkari said as many as 400 CBG projects are coming up within the country and this will generate demand for biomass in the form of crop residue. Making CBG with biomass will also generate lignin as a byproduct, which will be further refined to make bio-bitumen. A range of feedstock, from rice straw to bamboo, can be used, he said. The country requires bitumen of Rs 90,000 crore. Of this, the commodity worth Rs 50,000 crore is imported. Making it out of lignin will not only cut imports, but also reduce the cost by Rs 8/kg, he said. The use of rubber powder will also give a boost to another industry, he said.