Assam Public Works Department (Roads) plans to procure plastic wastes from the city to construct roads in a bid to battle the rise in cost of road buildings and help conserve the environment in the process.
Catching up with the trend of using recyclable wastes along with bitumen or as popularly known asphalt to construct roads, Assam PWD minister, Himanta Biswa Sarma, had initiated a pilot project to metal a stretch of 100 metres using the same on the Kahilipara-Dakhingaon Road on July 19.
“This technology is suitable for Assam as we have heavy rainfall which damage roads. The project will help decrease environmental impact from plastic waste, reduce construction costs and build stronger and durable roads. If the pilot project is successful, we will apply this technology while constructing roads across the state,” Sarma told the media here during the launch.
“As Guwahati generates the largest amount of plastic, if the pilot project proves to be successful, recyclable plastic will be procured from Guwahati mostly. Once started in Guwahati, we will then start procuring from other parts of the state too. This will help the city in reducing its pollution and the PWD to construct at a much cheaper cost,” Prahlad Kakati, PWD assistant executive engineer (new technology cell) said.
According to a recent study conducted by an NGO, Assam generates 2.99 lakh kgs of plastic every day, 37,000 kgs (17 per cent) of which is generated by the city.
Assam follows Meghalaya in implementing the technology with the latter constructing a stretch of 1 km in Nongkynjang village of West Khasi Hills using plastic waste. Tamil Nadu in southern India, that currently has more than 10,000 km lain with waste-plastic mix, was among the first states in India to adopt this technology.
Manipur is also planning to use plastic waste in building roads which will make it the third state in the northeast after Assam and Meghalaya to use plastic waste in road construction.
Explaining how plastic wastes are used to construct roads, Kakati said, “The process is very simple. Waste plastic bags are collected from households, roads, garbage trucks, dumping grounds, rag-pickers and waste buyers. The collected plastic is sorted according to their thickness. Generally, polythene of 60 microns or below is used in road construction. The plastic is cleaned and shredded to a size between 2.36 mm and 4.75 mm.
The aggregate mixture is heated to 165 degrees Celsius, bitumen of standard specification is added and then the shredded plastic is added. The amount of plastic to be added is 8 per cent of the bitumen. The resulting mixture is laid on the road surface at 110 degrees to 120 degrees Celsius.”
The waste plastic proves to be a more cost efficient method, as it does not need to be mixed with fine gravels in the last layer of metalling.
“Most of the times, we put three layers while constructing a road. The rock base at the bottom, the gravel mixed with tar and the last with fine gravel and asphalt. With this technology, according to our estimates, we can bring down the cost by at least Rs 21,000 per kilometre,” a PWD source said.
In terms of dexterity too, this technology proved to be helpful as the first road, Jambulingam Street in Chennai, built in 2002, has not faced any major damage even after 16 years.
“Waste plastic bituminous mixture helps build stronger roads with better load-carrying capacity, resistance to rainwater and water stagnation, increased binding and better bonding of the mixture, reduction in pores and potholes, reduced cost of construction and insignificant maintenance costs, apart from no plastic waste disposal problems,” Kakati said.
A central government order in November 2015 had made it mandatory for all road developers in the country to use waste plastic, along with bituminous mixes, for road construction. This is to help overcome the growing problem of plastic waste disposal in the country.
The technology for this was developed by the Plastic Man of India, Rajagopalan Vasudevan, a professor of chemistry at Thiagarajar College of Engineering, Madurai.
Plastic pollution affects wildlife, marine life and their habitats while discarded plastic clogs drains, resulting in artificial floods.