Can paving with plastic make a dent in global waste and make for a smoother ride? Only 9 percent of the 350 million tons of plastic that humans produce each year is recycled. Rest go into the landfills. From lower carbon emissions to fewer potholes, there are a number of benefits to building a layer of plastic into roads.While widely in use in India, it is still in its nascent stages in other countries. “I believe plastic roads, if done to scale, in combination with other uses for reclaimed plastic, like concrete and fuel, will offer an opportunity to absorb hundreds of thousands of tons, almost overnight,” Doug Woodring, founder of Ocean Recovery Alliance, said in an email to GreenBiz.
CHERMAINE LEE in FUTURE PLANET: On a road into New Delhi, countless cars a day speed over tonnes of plastic bags, bottle tops and discarded polystyrene cups. In a single kilometer, a driver covers one tons of plastic waste. But far from being an unpleasant journey through a sea of litter, this road is smooth and well-maintained – in fact the plastic that each driver passes over isn’t visible to the naked eye. It is simply a part of the road. This road, stretching from New Delhi to nearby Meerut, was laid using a system developed by Rajagopalan Vasudevan, a professor of chemistry at the Thiagarajar College of Engineering in India, which replaces 10% of a road’s bitumen with repurposed plastic waste.
New roads in India built near large urban centers are mandated to use waste plastic in their construction. The plastic that goes into roads would otherwise go to landfill or the incinerator.
FUTURE PLANET
India has been leading the world in experimenting with plastic-tar roads since the early 2000s. But a growing number of countries are beginning to follow suit. From Ghana to the Netherlands, building plastic into roads and pathways is helping to save carbon emissions, keep plastic from the oceans and landfill, and improve the life-expectancy of the average road.
Research suggests that “using waste plastic in road construction helps to improve substantially the stability, strength, fatigue life and other desirable properties of bituminous mixes, leading to improved longevity and pavement performance,” Michael Burrow, an engineer at the University of Birmingham and senior author of a global study of the technology, said in an email.
GREEN BIZ
By 2040, there is set to be 1.3 billion tons of plastic in the environment globally. India alone already generates more than 3.3 million tons of plastic a year – which was one of the motivators behind Vasudevan’s system for incorporating waste into roads. It has the benefit of being a very simple process, requiring little high-tech machinery. First, the shredded plastic waste is scattered onto an aggregate of crushed stones and sand before being heated to about 170C – hot enough to melt the waste. The melted plastics then coat the aggregate in a thin layer. Then heated bitumen is added on top, which helps to solidify the aggregate, and the mixture is complete.
While different companies are pursuing different approaches, the general idea is that waste plastic is melted and mixed with other ingredients for making road asphalt. Ordinarily, asphalt is composed of 90 to 95 percent aggregate — whether gravel, sand or limestone — and 5 to 10 percent bitumen, the black gooey substance extracted from crude oil that binds the aggregate together. When contractors add waste plastics — which can serve as an even stronger binding agent than bitumen — they often replace just 4 to 10 percent of the bitumen, although some methods call for much more. Plastic roads, therefore, are not solid ribbons of plastic — far from it.
GREEN BIZ
More here in Future Planet and in Green Biz.
RELATED: Pakistan’s annual plastic waste generation in 2020 was around 3.9 million tons, which is expected to increase to 6.12 million tons per annum by year 2050 as the use of plastic materials is on the rise. 25-30 per cent of the plastic waste is managed by the informal recycling sector. Over 70 percent (2.6 million tons) of the plastic waste is not recycled and ends up in the municipal waste stream (Gulf News).
