Plastic roads: The way forward?

Plastics account for 16 per cent of the total waste we generate. Like in other parts of the world, plastic has emerged as a serious environmental issue in Nepal as well. To deal with this, probably it’s time we started considering plastic roads

Roads made of recycled plastics are the future of the world. Urban development has made massive use of plastic materials which are now creating huge environmental threat due to its non-decomposable nature. Reusing plastic is not an easy task. Not only in Kathmandu but also all around the globe, it has become a burning problem. Plastic garbage in mega-cities, in rivers and oceans, has emerged as a big environmental issue.

Waste management has become a perennial problem in our cities as well. The Kathmandu Valley is one of the worst examples. While the streets littered with garbage, on the one hand, are killing the aesthetic beauty of the city, the rotting waste is posing a serious public health challenge. The main reasons why Kathmandu is unable to manage waste is the volume and our limited management capacity. And plastics make up a good amount of our solid waste.

A study conducted by the Asian Development Bank in 2012 shows that about 56 per cent of our waste consists of organic materials and 16 per cent plastic. While the organic part is decomposable, which can be converted into energy, bio-gas or manure, the non-decomposable plastic part of the waste is very troublesome.

The use of plastic materials like bags, bottles, wrappers, covers is ever increasing. Plastic litter also blocks the drainage system and flood the city during rainy seasons. The estimate shows that about 4,000 metric tons of plastic garbage is disposed every month in the Valley.

What can be the solution then?

Maybe it’s time we started paying attention to plastic road technology.

This is a fact that we need good roads which are least affected by rainwater and water stagnation, have no stripping with no potholes, strong and least cracking and can be constructed in less time and cheaply. How nice it would be if we had roads which can be fixed in no time when maintenance work is required.

Plastic roads have all these features. Further, we wish to manage our non-decaying part of the garbage – that is plastic – without burning, which generates harmful gases.

Plastic road is a green technology that uses plastic garbage to make roads. Plastic roads are made either entirely of plastic (as in the Netherlands and Australia) or of composites of plastic with other materials (as in India and Ghana). Plastic roads are different from standard roads as the latter are made from asphalt concrete, which consists of mineral aggregates and asphalt. The technology of plastic roads is relatively new but rapidly growing.

The technology was developed by the “Plastic Man” of India, Rajagopalan Vasudevan, a professor of chemistry at Thiagarajar College of Engineering, Madurai. He developed the technology in 2002 and first built a plastic road in his college.

Vasudevan’s inclination to keep experimenting led to yet another innovation. He decided to try creating a stone block with plastic coating and, in 2012, “plastone” came into existence. A plastone block is made from a mixture of waste plastic and stone. It has been found to withstand more pressure and it resists water percolation. In the professor’s department of chemistry, they have made plastone blocks using granite and ceramic waste, along with plastic waste. Plastic roads are now constructed in many countries like India, Nigeria, Australia, the Netherlands, Kenya and Ghana among others.

At least 11 states of India have used the technology to build more than 100,000 kilometres of roads. The government of India ordered in November 2015 that all road developers in the country use waste plastic, along with bituminous mixes, for road construction.

The most attractive feature of a plastic road for Nepal is its low operating cost and durability. It is cheaper as it uses recycled, post-consumer plastics than asphalt. Plastic-bitumen composite roads have better wear resistance than standard asphalt concrete roads. They do not absorb water and have better flexibility, which results in less rutting and less need for repair.

Road surfaces remain smooth, need minimal maintenance and absorb sound better. The use of plastic in road construction reduces the amount of asphalt. This is beneficial to the environment since asphalt is responsible for 2 per cent of global carbon emissions.

A study report published in a journal of Indian Engineering and Technology in February 2017 shows that the use of plastic saves Rs 320,000 per kilometre of road compared to the traditional method. This means if we are to pave road from Kathmandu to Kerung boarder, which is about 175km, it will save us Rs56 million.

Plastic roads have a hollow space that can be used to (temporarily) store water, thus preventing flooding during extreme precipitation. The hollow space can also be used for the transit of cables and pipes, thus preventing excavation damage. The patch-up process for potholes is very easy as roads can be created as individual pieces (sections), which can be switched out in case of damage. This is different from traditional ways of road repair.

Recently plastic road technology has been experimented in Pokhara on a small stretch of a road. This should be verified and if desirable, other cities can adopt the technology.

Satyal is professor at Department of Statistics, TU