A crusading Indian scientist is at the forefront of a movement to use more plastic technologies to fix India's failing roads. In 2002, Rajagopalan Vasudevan used his now-patented bitumin-modified plastic pavement on a 60-ft road with plastic-modified bitumen. Since then, almost 10,000 kilometers of Indian roads have been paved using his technique, which improves the tensile strength of the road and prevents pothole formation. When the layer of molten plastic filled the space between the gravel and bitumen it thwarted rain water from seeping in.
Plastic waste affects citizens and environments everywhere, but the impact is particularly pronounced in India. India produces 15,000 metric tons of plastic waste daily. In 2017, a garbage slide from a towering landfill killed citizens in East Delhi. However, this same plastic could also be part of the solution for another problem affecting Indians — potholes. It has been estimated that over 10,000 motorists are killed each year due to pothole-related accidents on India’s 5,472,144-km road network.
Experts and activists have been suggesting that more roads should be constructed from plastic waste by using a method proposed by an Indian scientist. These roads are said to be more durable, withstanding monsoon damage, tanks, and heavy vehicle traffic. They are also instrumental in waste recycling, mitigating against tragic garbage slides.
Vasudevan explains, “Plastic is mostly used in packing materials. The ban of plastics is not a solution. Being cheap and easily moldable it is available for effective use. The reuse of the waste plastics is the best solution for plastic pollution. Plastics being a byproduct of petroleum can have a compatibility with bitumen.”
In 2002, he tested the use of plastic roads on the campus of Thiagarajar College of Engineering, where he was a professor of chemistry at the time. Today, he is Dean ECA at the college and an outspoken proponent of waste management solutions.
Although the initial method was imperfect, Vasudevan persisted. “We developed a new technology where plastics were coated over the stone and that is mixed with bitumen to form the mix for the road,” he says. That initial 60-foot test road is still intact today, with no potholes or cracks.
Under this current method, thin-film plastics are finely shredded and used in hot-mix plants. In a heating chamber, tar is poured onto hot stone aggregates. When flakes of plastic are added, they quickly soften and form a baked-on polymer coating over each stone. According to a paper he co-authored in Construction and Building Materials, “the softened plastics have a tendency to form a film like structure over the aggregate, when it is sprayed over the hot aggregate at 160 °C.” The bitumen adheres more strongly to these coated stones, prolonging the service life of roads.
According to guidelines for the use of waste plastic in hot bituminous mixes, prepared by Indian Roads Congress, “Studies have revealed that waste plastics have great potential for use in bituminous construction as its addition in small doses, about 5-10%, by weight of bitumen helps in substantially improving the Marshall stability, strength, fatigue life and other desirable properties of bituminous mix, leading to improved longevity and pavement performance. The use of waste plastic thus contributes to construction of green roads.”
By using Vasudevan’s method for plastic roads, every kilometer of road saves around one metric ton of asphalt, costing approximately 8% less than a conventional road. “Plastics roads are highly durable and withstand for a longer period without any potholes for more than 10 years,” says Dr. Vasudevan.
According to Almitra H. Patel, member of the Supreme Court Committee for Solid Waste Management, plastic roads solve more than just potholes. When road shoulders are not well-maintained, the edge of the bitumen carriageway gets nibbled away and becomes a little crescent-shaped, making the road narrower. “And with the plastic roads, I’ve seen that these remain ruler-straight,” she says.
Patel contends that more plastic roads should be constructed. “It would be hugely beneficial for India’s economic development,” she notes. Patel says that companies responsible for producing problematic packaging and waste problems have an extended producer responsibility.
“These companies should be asked, don’t give money. Donate a shredder. Maybe one for every zone or group of wards, so that all the non-recyclable plastic can be shredded for our use in plastic roads,” she says. “Another group or the same group can donate a vehicle for transporting the shredded plastic from the dry waste collection centers within the town, to the hot mix plants on the outskirts of the town.”
The Government of India has called for a bituminous mix with waste plastic to become the default mode. After noting the environmental problems caused by plastic waste and the opportunity to improve the longevity and pavement performance of roads, orders from the Ministry of Road Transport & Highways stated, “The Ministry has decided to encourage use of plastic waste in the hot mix bituminous-wearing coat."
Other countries have also experimented with the use of plastic materials in roads and bridges. Some of these methods differ from Vasudevan’s polymer-aggregate-bitumen mix. KWS, a VolkerWessels company, has designed a plastic road that comes in prefabricated road parts, which can be easily transported and then combined onsite. Although the execution of the idea is different, the company also lists improved durability as one of their technology’s many benefits.
The United States Forest Service developed a plastic road concept that involves a PVC pipe mat. This system effectively facilitates short-term access to environmentally sensitive sites. It reduces damage to soils and vegetation by spreading wheel loads over an increased subgrade area. There is also a 90-foot plastic bridge on private land in Scotland, which was made from 50 tons of recycled, high-density polyethylene materials.