Q. How did the idea come about for your transformational project to use plastic waste to build roads?

A. To answer this, we need to start from the core problem that had to be addressed. We live in the Plastic Age today. 10 metric tons is the consumption for 2017. This is estimated to rise to 20 metric tons in 2020. Plastics have become common man’s friend. It is found in all the essential things in their lives. Plastics, otherwise polymers, have found uses in packaging, electrical, fertilizers, agriculture, toys and engineering materials, domestic appliances, building materials, etc. It’s most important application is in the packaging industry as carry bags, tea cups, sheets, films, multi layered films and thermocole, which comprises 35-40% of the total plastic consumed every year. But all these, once used, are thrown away or littered into the environment as waste, either in landfills or incinerated. These are non-biodegradable and mix with the municipal solid waste (MSW). Ultimately, these get collected in water canals, rivers and land. This results in water-clogging, stagnation of sewage water and poor hygienic conditions. Moreover, plastics are not bio-degradable. The accumulation of plastic waste everywhere is an eye sore for both citizens and tourists. Plastic waste in the MSW also contaminates the organic waste in the MSW which is used for manure conversion. That leads to a multiplier impact. In this process, plastic waste has become a major cause for environmental pollution.

It was to address this basic problem that we came with this idea of using plastic waste for road-laying. These plastic packaging waste materials (either mono-layer or laminated poly-layers made out of poly-ethylene, poly-propylene and poly-styrene; PVC is not used) can now be used for uses like road construction and block making, without affecting the environment. We patented this technology in 2002, and it was also coded by the Indian Road Congress in 2013 (IRC-SP-98-2013). I am also happy to share that we decided to give the technology of this to the Government of India for free – so that it serves and benefits all humanity!

Q. What are its advantages vs. the traditional method of road-laying?

A. The advantages are multi-faceted. It helps to use the plastic waste that would otherwise find its way to our landfills, rivers and seas; hence the disposal of plastic waste is no longer an environmental challenge. It helps avoid the entry of three tons of CO­₂ in the atmosphere, which would have occurred due to incineration. Reuse of plastic waste for roads is a suitable eco-friendly solution and helps avoid plastic pollution through landfills or incineration. Waste like carry bags, disposal cups, thermocole, multi layer films, poly-ethylene and poly-propylene foams can be used without segregation and cleaning. The other advantage is in the road’s quality. Plastic tar road has double strength, as compared to bitumen road. It can withstand heavy load and heavy traffic. It is not affected by rain or stagnant water. Hence, no pothole is formed. There is no rutting and raveling. The plastic tar roads we have laid are performing very well even after 10 years without any permanent deformations – that is saying something in a country where the average quality of roads leave much to be asked for. It can be used for all types of roads – from national highways to rural roads. It does not require any new machinery. That also means the cost of maintaining an existent road is less. This is a cheaper method because it uses less bitumen. By using this process, an extent of 10% of the total project cost will be reduced due to the reduction in the use of bitumen and maintenance (apart from the indirect savings from the effects of plastic pollution).

The use of plastic waste in this technology is high, and we can use 10-15% of plastic waste to the weight of bitumen. Moreover, the plastic waste which were otherwise thrown into the streets, landfills or rivers can now get economic value-addition – the waste becomes a productive resource! The use of plastic waste directly creates a demand for it in the market. In many states, self-help groups and NGOs are already involved in the process of the collection of plastic waste. They collect and shred the waste and sell it to the concerned authorities for Rs. 20-25 per kg. That becomes a source of employment for those people.

Q. Have these plastic roads been officially tested for quality?

A. The performances of the roads laid were studied under the specifications of the Central Road Research Institute and the guidance of the Central Pollution Control Board. Their results were highly encouraging. Monitoring of the test roads was carried out using structural evaluation, functional evaluation and conditional evaluation studies. The results obtained from the roads laid from 2002 to 2006 helped conclude that these roads are performing very well despite their age. Under similar conditions, most bitumen roads are not performing that well. The plastic roads have not developed even a small crack or pothole. Moreover, these roads were distributed over different localities exposed to various environmental conditions (temperature, rainfall, etc.) and yet they are all performing well.

Q. Please could you explain briefly how the technology works?

A. The process itself is very simple and in situ, no external industries are involved. In simplest terms, plastic waste (carry bags, cups, thermocoles and foams) are shredded into small pieces (between 1.6-2.5mm). The granite stone is heated to around 170⁰c. The shredded plastic waste is added to the stone. It gets melted and coated over the stone in just 30 seconds. Then the bitumen is added and mixed. The mix is used for road construction. The consumption of bitumen is less to the tune of plastic used. The plastic basically acts as a binder between the stones and the bitumen. It results in a better mix for road construction and the quality of the stone improves as it closes the voids. The temperature is far less than what it would have taken for the plastics to decompose and produce toxic gases which would have caused air pollution. So no toxic gases from plastics are released in this process. 

Scientifically, plastics are the byproduct obtained from petroleum refineries. Hence, they are hydrocarbons only. Bitumen is also a byproduct obtained from petroleum distillation. Hence there should be compatibility between plastics and bitumen, and also with the other products from petroleum distillation. This behavior was tested and proved technically during our research. Attempts were made to modify the bitumen by dissolving plastics in bitumen. This was partly successful but we could dissolve only lower percentages of plastic, i.e. 1-3% in bitumen. Moreover, this posed challenge to scale up and the cost was higher. We researched for an alternative method. This new method has been developed by coating plastic waste over hot stone aggregate, which is then used for road construction. It consumes more plastic waste, i.e. 10-15%.

We have also developed a cold-mix road-laying process using emulsion and plastic-coated aggregate, which can be used for laying roads in colder regions where the heating of the aggregate is not easily possible. The reuse of road scrap in road-laying is another find. Normally when new roads are laid, the existing top-layer is scraped out and a fresh layer laid over that to avoid an increase to the road’s height. This scrap is usually disposed off as waste. We have developed a modified process for the reuse of scrap in road-laying, by mixing the scrap and the fresh mix in a certain pre-defined ratio. The polymer-coated aggregate can then be used in the process of preparing the fresh mix. Due to this, no scrap is wasted and only a certain percentage of the raw materials is now demanded (a reduction in the cost to that extent). The height remains unaltered. This technology has already been implemented in some stretches of the national highway network. 

Q. You must have faced some challenges too to implement this new technology?

A. We also faced challenges. While plastic waste is available in large quantity, it is not properly collected to be made available for this purpose. Self-help groups of village ladies are being employed for the collection of plastic waste. They have been given financial aid and support by the government. But since the road laying contractors are not in favor of this technology (because the plastic roads are durable in nature and need not be re-laid soon, hence bad for their business), the self-help groups are not able to get the expected business. So the biggest challenge is the resistance from road contractors. The plastic waste is currently added manually in the process of laying the roads. But if this were automated, it would be better. The awareness amongst the technology group is also less. Awareness camps can help the younger generation, but it is not properly promoted despite government schemes like Swachh Bharat. Ultimately, the role of politician is very important, as only they can promote this technology. So while this technology is made in India, it is yet to take off as expected!

Q. So how far has it been adopted, and how can it implementation be scaled up?

A. More than 50,000 km. of roads have been laid using this technology. Nearly 11 Indian states have started implementing this. Details of roads laid are available in the NRRDA site. Both the government and the private sector have appreciated this technology. The government is using the PMGSY scheme fund for laying plastic roads in the rural sector. The Central Pollution Control Board published the guidelines for laying plastic road in 2006 itself.

In plastic tar road, the technology can be used in both mini hot mix plan and in central mixing plant. Hence there is no problem of scaling it up. This technology is simple and can be adopted easily with less cost. Overall, India has not less than 41 lakh km. of road network, of which 66, 000 km. are highways and 24 lakh km. are rural roads, state highways etc. In India, major road-laying is done by the government, either the Panchayat, municipalities or corporations. The NHAI is doing major road works in India. In essence, scaling up depends a lot on these government bodies.

Apart from India, other countries like Indonesia, Malaysia, Brunei, South Africa, etc. are requesting for this technology to be adopted in their countries, and steps are being taken to extend the technology-transfer to them.

This project also insists in the practice of good garbage culture amongst the public. The project can become a success if the segregation of plastic waste at the source is practiced all over the country. When the plastic waste mixes with the MSW, the segregation becomes tough. The project also suggests various possibilities in collecting plastic waste at source, like the two-bin system, awareness camps and own your ownership technique. Awareness camps and lectures are being organized to educate the school students and garner help to collect the plastic waste at the source. It has been partly successful.

Q. How much plastic is needed for this?

A. For a 1 km. length of road with a width of 3.75 m.,  we need one ton of plastic. That is roughly the equivalent of about 10 lakh carry bags. It also means one ton less of bitumen is demanded, and we all know how expensive bitumen is. India has 41 lakhs km. of roads. If all of them were converted/made to plastic tar road, we would need more than 100 lakh tons of plastic waste. But India does not have that quantum of plastic waste; it only has 16 lakhs tons or so. So it is a sort of challenge.

Q. What is your view about the government’s response to plastic pollution?

A. Plastic manufacturing is a major industry in our country, which engages over 10 crore people. Moreover, the plastic industry comes under the subsidy industrial scheme of the government. Hence, outright banning the use of plastics will result in economic disorder in the country. To avoid this situation, the government had taken steps to reduce the use of plastics like increasing the thickness of carry bags, creating awareness to reduce their use, recycling of recyclable plastic waste and the reuse of waste plastics. The banning of plastics will not be an absolute solution for plastic pollution. Finding alternative solutions to plastic pollution is the need of the hour. This situation motivated us to work on plastic waste and dispose it in an eco-friendly way.

The government is also taking measures under Swachh Bharat programme, which has become useful in this objective. A system has to be developed to collect the plastic waste, and shred it for the construction of roads. But cooperation from engineers and contractors is also needed to make this work. If the system works well, then the problem of plastic waste disposal can be almost solved, and we can leave a better and cleaner world for our succeeding generations which they can feel proud of!

Q. What are the other innovative projects you are working on since then?

A. We have also worked to develop other products like Plastone blocks as a substitute for paver blocks. It is a synthetic granite block which does not require sand, water, bitumen, cement or adhesive. It contains only plastic and stone, and consumes a large amount of plastic waste. It can be used as roadside paver blocks, water-canal lining, compound walls, lawn flooring, etc. Its manufacturing process helps reduce the use of cement, sand and water, since the process uses plastic waste as a binder. By using these technologies, almost all of the plastic waste in the country can be reused and the disposal of plastic waste will no longer be a problem. Moreover, we have also developed other products like polymer modified bitumen roofing sheets, corrosion resistant reinforced steel bars for construction purpose under this project, which use plastic waste as a binder.

Secondly, the technological development today in both electrical and electronic products has resulted in the production of e-waste which has larger toxic compounds. Their disposal also needs to be attended to. Our work is ongoing in this direction. This growing problem needs to be attended through appropriate technology so that the benefits can reach the common man.

Q. Lastly, tell us a bit about the recognition this technology has received?

A. The patent for this technology was obtained in 2002. Since then, the CPCB approved the project in 2005, the NRRDA issued guidelines for laying plastic roads in rural areas in 2006, the Ministry of Environment and Forest published the notification for laying plastics road in forest areas in their Gazette in 2008, the Indian Road Congress published the coding for road laying using dry process in 2013 and CIPS published a review on the plastic tar road in 2015. In 2015, the inventor received the TECH Icon of India Award, presented by Honbl. Prime Minister of India. The Mewar Foundation, Udaipur awarded it the Maharana Udai Singh environmentalist award in 2017. A series of TEDx lectures have also been delivered on this in Goa, Mumbai and Chennai. The inventor also received the Padma Shri Award, India’s fourth-highest civilian honour, in 2018 for his contribution towards India’s betterment! 

• Prof. Rajagopalan Vasudevan is a noted scientist and Dean at Thiagarajar College of Engineering, Madurai. He developed the innovative technology to reuse plastic waste to construct roads. This method is used commercially. He has also developed products like Plastone using plastic waste. As a recognition for his services to India, he was awarded the Padma Shri Award in 2018.

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