But using polymer-modified bitumen – bitumen mixed with polymer glue made from shredded waste plastic – during construction makes the roads much more durable.
Bangladesh has around 21,000 kilometres of highways, 30% of which is difficult to use due to the cracks and potholes.
Many countries in Europe have been constructing plastic roads since the 1970s, while India took its first initiative in 2000.
The Jambulingam Street in Chennai, capital of the Indian state of Tamil Nadu, is one of India’s first plastic roads. Over the years, they have proven to be surprisingly durable and have yet to develop any potholes, rutting, ravelling or edge flaw, according to a report by the Guardian.
At present, India has over 33,796 kilometres of plastic roads, roughly half of which is in Tamil Nadu alone. Most are built in rural areas, but a small number of roads have also been built in the cities of Chennai and Mumbai, the report further says.
The plastic roads are also a wonderful solution to plastic litter, as waste plastic material can be recycled and used.
India’s success story gives the Bangladeshi experts hope that plastic roads can work here as well.
“It is possible to use polymer-modified asphalts [another term for polymer-modified bitumen] to build plastic roads in Bangladesh,” said Shamsul Hoque, professor at the department of civil engineering in Buet. “As far as I know, the government has already taken an experimental initiative to build a plastic road,” said the professor, who is also a consultant for several road and bridge construction projects.
He further said polymer-modified bitumen would be used to construct high-stress roads and expressways in future.
However, when asked, Ebne Alam Hasan, chief engineer at the Roads and Highways Department, told the Dhaka Tribune that it was not yet possible to take on such an initiative.
“There are many limitations, and we lack the expertise and the resources,” he added.It is not as simple as it sounds“It is difficult to collect the necessary waste plastic and then turn it into the liquid glue in order to be mixed with bitumen,” said Prof Shamsul Hoque.
“But nowadays, machineries are available that can make the process easy,” he added.
According to experts, polymer-modified asphalts are made from virgin polymers and sometimes crumbs of rubber collected from old tires.
Shamsul Hoque said: “In the past, a huge number of used tyres were dumped at dumping stations in the US and there was no way of recycling them, which became a problem for the US government. It was a Bangladeshi scientist, Prof Shahajada Mostak Hossain, who discovered that the tyres, when cut into small size, can be heated until it takes a liquid glue-like form which looks similar to bitumen. Further research revealed that it could be used like bitumen to coat stones. Road contractors then began using that liquefied tyre rubber with bitumen in road construction, strengthening the roads.”Also read - Will it save the environment? | New material will extend runway life by 40 years | Are plastic roads cost-effective for Bangladesh?
Polymer-modified bitumen has higher tolerance for heat, compared to the conventional bitumen. Plastic roads will not melt until the temperature rises beyond 66 degrees Celsius, which is higher than the threshold temperature of 50.2 degrees Celsius for ordinary roads. “Polymer plastic can absorb more heat than bitumen, so plastic roads are less likely to crack or melt in extreme heat.” However, the cost of such technology may increase the expense of road construction by 30-50%. But Shamsul Hoque is not worried about that. “The world now follows the theory ‘Fit and Forget.’ If we build an infrastructure in a sustainable process, people will agree to bear the additional cost.”
