Less Plastic, Better Roads

Roads constructed from waste plastic were innovated in India almost two decades ago, but they are hardly being paved

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Dr. Rajagopalan Vasudevan says it is the love of his countryfolk that made him popular as the Plastic Man of India. The 74-year-old chemistry professor is known for innovating plastic-coated bitumen in his laboratory at Thiagarajar College of Engineering in the southern Indian city of Madurai. Created from waste plastic, the material is being used to pave roads in India since 2002.

“As a teacher of polymer chemistry and consultant to various firms, my mind is always looking for solutions to problems,” says Vasudevan.

In 2001, discussions about a nationwide plastic ban worried him. “Plastic is an important resource, a versatile material and a poor man’s friend,” he says.

Vasudevan started thinking of ways to reuse and recycle plastic waste.

“I thought, since both plastic and bitumen are by-products of petroleum, why can’t the two be mixed?” he says.

That’s how the idea of polymer-modified bitumen was born. Vasudevan tested the concept and improved it until a material that could withstand higher loads was developed to build more durable roads than the conventional ones.

“When plastic is added to gravel, it binds it well with bitumen, preventing water percolation,” says Vasudevan.

Roads paved from plastic-modified bitumen are resistant to developing cracks and potholes. Therefore, the material is a huge plus for Indian roads, highly unpopular for their poor safety. According to a recent report, 10 people died every single day in India in 2017, due to accidents caused by potholes alone.

Vasudevan’s patented process involves drying and shredding discarded plastic packaging, thinner than 80 microns—made essentially of polyethylene, polypropylene and polystyrene—into 2 mm to 4 mm pieces.  When sprinkled over gravel heated to 170°C, shredded plastic melts instantaneously. It coats the gravel, after which, bitumen is added and the mixture is ready for road laying. For construction of a kilometer of road, the mixture uses a tonne of plastic, equivalent to 100,000 plastic carry bags. Plastic replaces a fraction of the costly bitumen in the road-laying mixture, cutting costs. “The cost of road laying is reduced to one-sixth as opposed to a conventional bitumen road,” Vasudevan says. “Waste plastic becomes an important resource again,” he emphasises.

Vasudevan explains that the percentage of bitumen replaced by plastic may vary from 5% to 10% depending on the climatic conditions of the region where road laying is done. Suitable for all climatic extremes, Vasudevan’s technique has been also used in Indonesia and Bhutan.

Plastic asphalt has greatly improved the quality of roads in India.
Polymer-modified bitumen, which uses plastic waste has greatly improved the quality of roads in India. Photo Creative Commons CC0_PXHERE

According to the Central Pollution Control Board, India produced 26,000 tonnes of plastic waste per day in 2017-18, 60% of which was recycled. India’s recycling rate is way higher than the global average of 20% and its consumption at 11 kg (in 2014-15) is less than half of the rest of the world. Even then, a significant amount ends up in oceans and landfills polluting water bodies and soil and killing marine life and stray animals.

Packaging accounts for a third of India’s plastic consumption. Chips and confectionary packets form the largest part of the plastic waste—about 19% —which is exactly what plastic paved roads utilise. Some of them are single-use plastics, which India has committed to phaseout by 2022.

Vasudevan claims that over 100,000 km of roads in India—which has the world’s second largest road network—have been paved using polymer-modified bitumen developed by him.

“It happened due to the blessings of Dr. APJ Abdul Kalam,” he recalls, referring to the late Indian scientist who served as president from 2002 to 2007. When Kalam visited Vasudevan’s college as a chief guest for a function in 2001, he was fascinated by Vasudevan’s idea and encouraged him to lay out the first stretch of road within college premises. With support from the college management, the job was done swiftly. “It’s been almost 20 years and that road still doesn’t have cracks or potholes,” Vasudevan says. “Dr. Kalam promoted the idea and became the biggest ambassador for my work.”

In 2015, the Indian government mandated the use of waste plastic in the construction of bitumen roads within a periphery of 50 km in cities with a population greater than 500,000.

And yet, all Indian states haven’t been aggressive in incorporating the idea.

“Frankly, it’s quite frustrating,” says Ahmed Khan, who runs a business to manage plastic waste in the city of Bangalore, the capital of the state of Karnataka. In 1996, he conceptualised a process for creating plastic-blended bitumen for road laying, which was verified and green lighted for use by India’s Central Road Research Institute in 2002. Khan’s company has been offering the material, technology and on-site execution to construct roads across India, but so far just over 4,000 km have been laid using his process.

Experts point towards the corrupt highway contractors who would be denied their source of income through frequent repeat contracts, if the durability of the roads rose. Khan blames it on the lack of political will. “Imagine how much the environment would benefit if this industry was allowed to flourish,” he says.

Main image: Every year millions of tons of plastic are deposited in landfills all over the world. Photo Tom Fisk/Pexels

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