Expert Expressions
Managing waste through paving roads with plastic
India is pioneer country in building plastic roads. In 2001, Professor R. Vasudevan, of college of engineering, Madurai invented the technology for making plastic roads. The first plastic road in India, Jambulingam Street, was built in 2002 in Chennai .This road did not show any signs of wear and tear even after fifteen years. In fact, it proved to be stronger than normal asphalt roads. For every ton of bitumen saved, a ton in CO2 emissions is saved (Bitumen is extracted by heating petroleum which emits CO2). Using plastics saves three tonnes of carbon dioxide for every kilometre of road. A rough calculation indicates that using plastics also saves about 670 dollars per kilometre of road. We can safely say that plastic roads are environmentally friendly and also save money.
The technology of making roads using plastic waste is also very simple. First, the shredded plastic waste is scattered onto an aggregate of crushed stones and sand before being heated to about 170 degrees, which is hot enough to melt the waste (heating plastics beyond 270 degrees C creates carbon emissions).The melted plastics 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 for paving the roads. Ordinarily, asphalt is composed of 90 to 95 percent aggregate –whether gravel, sand or limestone—and 5 to 10 percent bitumen that binds the aggregate together. Waste plastics often replace just 4 to 10 percent of the bitumen, though some methods call for much more.
On the basis of experience gained in Tamil Nadu and a few other places, the Government of India in 2016 made it mandatory to use plastic waste in constructing roads near cities with a population of 5 lakh or more. In India, where 50 percent of the country’s roads were unpaved only a few years ago, about 14,000 miles of new roads have been built since 2016. This has given a great opportunity in India to put plastic waste to use quickly. Research has shown that roads built with waste plastic last longer, have better load bearing capacity, are better resistant to water damage, crack less, have fewer potholes and can tolerate wider temperature variations as compared to asphalt roads . Plastics can also be used for road repairs. However, one concern about plastic roads is that they will shed microplastics. But no one has reported that this has occurred.
Following India’s example, plastic roads are now being built in more and more countries around the world. The technology, meanwhile, is gaining ground in Britain, Europe, and Asia. Several countries – South Africa, Viet Nam, Mexico, the Philippines, and the United States – have built their first plastic roads only recently. Plastic roads give us a tremendous opportunity to reclaim and use large amounts of plastic waste very quickly. Out of 350 million tons of plastic that is produce globally each year, only 9 percent is recycled. India alone already generates more than 3.3 million tonnes of plastic a year. In this light, plastic road technology offers a very effective strategy for preventing sending of plastic waste in the oceans and landfills, and makes it a vital practice for strengthening sustainable economies world over.
One important aspect of using plastic waste for road making is that various types of plastics do not have to be separated before use. Many different types of plastics can be added to the mix: carrier bags, disposable cups, multi-layer films and polyethylene and polypropylene foams have all been used into India’s roads, and they don’t have to be sorted or cleaned before shredding.
The chemicals firm Dow has been implementing projects using polyethylene-rich recycled plastics in the US and Asia Pacific. The first plastic road in the UK was built in Scotland in 2019 by the plastic road builder MacRebur, which has laid plastic roads from Slovakia to South Africa. MacRebur is a leading manufacturer of plastic paving materials. It has been estimated that every ton of MacRebur mix contains the equivalent of 80,000 plastic bottles ; every kilometre of road paved with its product contains the weight of nearly 750,000 0 plastic bags. Plastic material is broken down to the size of rice grains, bagged and sold to construction and asphalt companies globally. MacRebur has also found that incorporating plastic helps roads cope better with expansion and contraction due to temperature changes, leading to fewer potholes – and where potholes do happen , filling them in waste plastic . The UK government recently announced 1.6 million pounds for research on plastic roads to help fix and prevent potholes.
Pursuing a different approach, the company PlasticRoad in the Netherlands avoids traditional asphalt altogether. This company builds paths with hollow modules made of single-use discarded plastics. PlasticRoad built the world’s first recycled-plastic cycle path in 2018, and recorded its millionth crossing in late May 2020. The company shredded , sorted and cleaned plastic waste collected locally, before extracting polypropylene from the mix—the kind of plastic typically found in festival mugs, cosmetics packaging, bottle caps and plastics straws. Unlike the plastic-tar roads laid in India, PlasticRoad does not use any bitumen at all. PlasticRoad material consists almost entirely of recycled plastic, with only a very thin layer of mineral aggregate on the top deck. Each square metre of the plastic cycle path incorporates more than 25 kg of recycled plastic waste, which cuts carbon emission by up to 52 % compared to manufacturing a conventional tile-paved bike path. In Ghana, Nelplast mixes shredded plastic waste with sand and moulds the mixture into pavement blocks.
With India having road networks growing at a rate of nearly 10,000 km of roads a year, the potential to put plastic waste to use is considerable. It is hoped that plastic roads will continue to gain popularity, not only for environmental reasons, but for their potential to make longer-lasting, more resilient roads. Of course, the importance of curtailing all unnecessary use of new plastics cannot be over-stressed. If we keep producing, using and throwing more and more plastic, we will never be able to manage it in a sustainable way. But paving the roads with plastics has shown an important way of recycling and reusing the plastic waste.
Leave a comment