More than a decade after a short stretch of road in Thimphu demonstrated the potential of using plastic waste in road construction, the technology is set to be deployed on a much larger section of one of Bhutan’s busiest highways.
Project DANTAK and Green Road are preparing to resurface 6.5 kilometres of the Chuzom-Babesa section of the Phuentshogling-Thimphu highway using shredded plastic waste mixed with bitumen. The work, estimated to cost around Nu 52 million, is expected to begin within the next two weeks.
The project draws on the experience of a 150-metre road near the Olakha workshop area in Thimphu, which was constructed by Green Road in 2015 as a pilot initiative.
Green Road, the first and only company in Bhutan to use waste plastic for blacktopping roads, incorporated shredded plastic into the bituminous mix used for the Olakha stretch.
Within eight months of its construction, the Department of Roads declared the trial successful. At the time, officials reported that the surface had remained smooth and free of potholes and had not required maintenance.
Although the pilot was initially intended to be monitored for five years, the road continued to carry traffic well beyond that period. Minor repairs were undertaken on a section of the road in 2023, eight years after it was built, while much of the original stretch continues to remain in use.
The durability demonstrated at Olakha has now encouraged the application of the technology on a larger scale.
Under a memorandum of understanding signed between DANTAK and Green Road, around 20 metric tonnes of shredded plastic waste will be incorporated into the resurfacing of the highway section. DANTAK expects the work to be completed within three months.
DANTAK Chief Engineer Brigadier J S Dhadwal said using discarded plastic in roads offers both an environmental solution and an engineering advantage.
“Plastic takes thousands of years to deteriorate, so using it in roads will help with its proper disposal,” he said. “It also gives the road additional strength, especially on the Phuentshogling-Thimphu road, where there is a lot of rainfall.”
He said the technology involves mixing shredded plastic with bitumen in carefully determined proportions, resulting in a road surface that is stronger and more durable.
While constructing plastic roads can involve a somewhat higher upfront expense, DANTAK expects the longer service period to offset the additional cost.
According to the chief engineer, the plastic has to be properly dried and shredded before being added to the road-building material, which increases the initial expenditure. The technology also requires specialised handling.
However, the new highway project will carry a five-year defect liability period, compared with three years for a conventional road.
“If we take into account the maintenance cost during those two years, the overall cost is at par with, or nearly the same as, a normal road,” Brigadier Dhadwal said.
Apart from potentially improving road durability, the project could provide another avenue for managing plastic waste by converting material that would otherwise remain in the environment for decades into an input for infrastructure development.
For DANTAK, the initiative adds a new technology to more than six decades of road construction and maintenance work in Bhutan. The organisation has been operating in the country since 1961 and has completed more than 1,650 kilometres of blacktopped roads.
The upcoming Chuzom-Babesa resurfacing project will now provide a larger test of whether the results seen on the small Olakha pilot can be replicated on a heavily used highway exposed to demanding weather and traffic conditions.
