Making inroad into plastic-less society

At a time when the world is worried over the massive accumulation of plastic wastes on its surfaces, which will threaten the very existence of the human race if not checked immediately, Dr R Vasudevan, Dean ECA & Prof. Department of Chemistry of Thiagarajar College of Engineering, Madurai, has an answer for this. He has done the country proud by introducing a technology where plastic wastes can be recycled for laying tar roads. These roads are not only stronger and durable, but also cost-effective and environment-friendly.

After a decade's of hard work and persistent efforts, Vasudevan’s invention of a technology to use plastic waste to lay roads, patented by TCE, finally got a shot in the arm last month with the Centre approving its wider application. KR Iyer speaks to the ‘Plastic Road Man', as he is  fondly revered in Madurai, about his vision and mission.

·         Can you give a brief note on how plastic wastes are being used in construction of roads?

Dr Vasudevan: Plastics are always common man’s friend. It finds its use in every field and the consumption of plastics increases day by day. Nearly 50% of the plastic consumed is used for packing. The most used plastic materials for packing are carry bags, cups, thermocoles and foams. These materials are made from polymers like Polyethylene, polypropylene and polystyrene. (The tubes and wires are made out of poly vinyl chloride).

These materials, once used are thrown out or littered by us more because of wrong culture. They mix with Municipal Solid Waste. As they are non-biodegradable, the disposal becomes a problem and they cause environmental pollution as they are disposed either by burning or by land filling.

Yet these packing materials (either mono layer or laminated poly layers made out of poly ethylene, poly propylene and poly styrene) can be easily used for various uses like road construction and block making, without affecting the environment. (Poly Vinyl Chloride is not used here) and it is the best way to dispose the waste plastics.

Plastics as a Binder:

These plastic materials when heated to around 120⁰c to 150⁰c, they melt and in their molten state they can be used as a binder. Only if they are heated to temperature more than 250⁰c they may decompose producing gaseous products which results in air pollution. Coating molten plastic over granite stone can be done around 150^o C and the coating helps to bind with bitumen strongly resulting in better mix for road construction and the quality of the stone also improves by closing the voids.

PVC is not used due to its toxic nature.

Waste Plastics for Road construction:

Plastics waste is shredded into small pieces (between 1.6mm – 2.5mm). The granite stone is heated to around 170⁰c. The shredded plastics waste is added to the stone. It get melted and coated over stone in just 30 seconds. Then the bitumen is added and mixed. The mix is used for road construction. From rural roads to National High ways all types of roads can be laid using this technique.

·         How does it save money and environment?

Dr Vasudevan: Waste plastics like carry bags, disposal cups, thermocoles, multi layer films and polyethylene and polypropylene foams can be used without segregation and cleaning. The process needs no new machinery and it is in situ process. The overall consumption of bitumen is less by 10 to 15% and thus the coat is reduced. By laying one km single lane of plastic road, 10 lakh carry bags are consumed with a saving of 1 ton of bitumen (Rs 40,000). 

It also helps to avoid the entry of three tons of CO­₂ in the atmosphere, if it is otherwise disposed by burning. Value addition to waste plastics is being created. Use of pavement scrap waste for plastic tar road reduces the cost by 50%.

 

• How strong are the Plastic Tar Roads compared to conventional ones?

Plastic tar road has double strength, compared to ordinary bitumen road. It can withstand both heavy load and heavy traffic. It is not affected by rain or stagnated water. And hence no pot hole is formed. There is no rutting and raveling. The life of the road is not less than seven years and there is no need for maintenance expenditure. Performance studies of the plastic tar road were carried out as per Central Road Research Institute specification and the results are very good. It has been published by CPCB and NRRDA as monographs.

The bitumen mixed with plastic flakes made from domestic wastes displays better hardness, better resistance to water penetration and hence lasts longer. Domestic wastes falling into categories such as polyethylene, polypropylene and polystyrene can be converted into flakes or granules and be mixed with the aggregate. Alternatively the plastic can be mixed with heated tar and later mixed with the gravel. Polyethylene can be used up to five per cent and polystyrene 20 per cent and so on, the professor said.

 

• What is the response from the state and central government?

Dr Vasudevan: There are a few states already started laying roads using plastics. They are Tamil Nadu, Pondicherry, Maharashtra, Andhra Pradesh, Kerala and Goa. The Centre has given its consent to use the technology in highway projects. 

But I feel that still more states need to adopt this technology. The awareness is lacking. Municipal Corporation should come forward to collect domestic waste, waste from public houses and markets using double bin systems. School student service may be used. It will also help to create awareness among them. 

Waste plastics by themselves are not a problem. Thinner films betters can be  easily used for road construction. The increase in thickness only helps to increase the consumption of raw material more and more.

It is the human problem. Man need to develop the habit of segregation. The authorities like Municipality, Corporation, Associations, and NRI can join to help the segregation.

A study on the performance of plastic tar road and plain bitumen road is given below.

 

 What is the response from the Tamil Nadu government?

Dr R Vasudevan with former President Dr APJ Abdul Kalam

Dr Vasudevan: The Tamil Nadu government had sanctioned more than  Rs 150 cr for laying plastic tar road in all corporations and municipalities. They have also sanctioned an amount of Rs 200 cr for Chennai Corporation alone. The Corporation had already started laying roads in city.

About the Growth of Plastic Tar Road

• The process of using waste plastics for road laying was developed in the year 2001. This was very much appreciated and encouraged by former President Dr. APJ. Abdul Kalam. The process was patented in 2002. The first plastic tar road was laid in October 4^th 2002 at Lenin Street, Kovilapatti. After the meeting of the then Chief Minister of Tamil Nadu and as per the instruction from the CM office the DRDA, Tamil Nadu encouraged the process and more than 2500 km of plastic road was laid all around Tamil Nadu up to the year 2006 (in all districts).

• The then Tamil Nadu government has also published a pamphlet, detailing the road laying process and the list of places where plastic road laid through DRDA. In an average nearly 40 km of road was laid in each district under DRDA program.

•  Many corporations like Chennai, Trichy and Madurai came forward to lay the plastic tar road and the plastic manufacturers also supported the process.

•  Then the process was geared up with the help of Central Pollution Control Board, New Delhi. They have signed two MoU with TCE 1. For releasing a guidelines book on laying of plastic tar road and 2. For the performance studies of plastic tar road (cpcb.nic.in).

• The plastic tar road technology gained its importance all over India and states like Kerala, Karnataka, Goa, AP and West Bengal are laying plastic tar road from 2005 to till date. The government of Kerala has honored Dr. R. Vasudevan by including him in the Kerala Government committee for the disposal of waste plastics.
• The pollution control board of Himachal Pradesh laid a model road during the period September 2009 at Shimla. After studying the performance of this road, they have laid more than 140 km of plastic tar road in the Himachal Pradesh till date. 
• The Department of Science and Technology, New Delhi had sanctioned two projects during the year 2005 -2008 and 2009-2012 for the studies on the technical issues of plastic waste management under Green Chemistry. The two projects costs around RS 1Crore. 
•   Invited lectures were given in many national and international conference at all state capitals in India and in widener university, Philadelphia, USA. It was highly appreciated by the Japanese professors and many of our engineers of high reputation. 
•  Recently in January plastic roads were laid at the TATA NAGAR, Jamshedpur. 
•  Former election commissioner Navin Chawla, during his visit to Madurai, had a special session at Madurai airport to discuss about the plastic tar road. 
•  Though the contractors are worried about a long life of the plastic tar road, many panchayat board chairmen are very much interested in this work. 
• Recently in the year 2010 the National Rural Road Development Agency in consultation with us, have published a Guidelines for laying plastic tar road laid. More recently the Ministry of Environment and Forest has published a gazette notification in their waste management rules book regarding the laying of plastic tar road by the municipal corporations of India. 
• Our present Chief Minister of Tamil Nadu has included in her parties election manifesto that the state will be freed from plastic menace and rural roads will be converted into plastic road using the process developed by the Thiagarajar College of Engineering. 
•  Collection and segregation of domestic waste are being popularized through the awareness camps conducted at various schools in and around Madurai and a school at Melur near Madurai laid plastic tar road in their school campus itself by using the waste plastics collected by the students. 
• A women organization SORPTOMISTIC has come forward to take the message to the mass for effective collection of waste plastics and safe guarding of Municipal Solid Waste (Which is a source for good manure) and it has already started the program in 25 schools at Madurai. 
• The works has been published in various international and national journals 
• A technical report on these work was sent to Indian Road Congress and it was published is the High ways Journal during the year 2004.
• Another technical publication came in the year 2010 from the International Journal of Pavement Research and Technology, China. 
• The process gained recognition throughout India and lecture demonstration is being arranged at many places by the public. 
•  India has more than 3.314 million kms of road length of which 70% of road is yet to be converted into tar road. They can be converted in to plastic tar road. We may need more waste plastics than what is available. All the plastics waste will be used and the roads will be strong and good. The disposal of plastic waste is no longer a problem.

“Let us understand the importance of waste plastic and good garbage culture - Let us make the environment clean.  Don’t litter plastic on road but use it for road construction.” __ Dr R Vasudevan

India wakes up to plastic roads

Using plastic wastes for laying roads is fast catching up among Indian cities and Indian government is mulling to formulate national level policy to use the technology on highways roads.

 Though several cities in India have banned usage of plastics, the disposal of a large quantity of non-biodegradable wastes being accumulated daily has become a challenging task for the governments and a worrying factor for environmentalists. Though re-cycling of plastics is addressing the issues to certain extent, it’s still lot to done. Using waste plastic materials to lay roads is a new concept, fast catching up in India.

Tamil Nadu has become a pioneer in using this technology invented by Chemistry professor Vasudevan of Thiagarajar College of Engineering in Madurai. Now, encouraged by the use of plastic in road laying in Tamil Nadu, the Centre is mulling a national level policy on its usage on national highways and other state highway roads. Mumbai too has tested plastics on road laying and found it to be a viable solution for frequent re-laying of roads after every monsoon.

"Using plastic in laying roads will increase the life of roads. We have to prepare a national level policy on this. We are talking over this," Environment and Forests Minister Jayanthi Natarajan told reporters on the sidelines of the seventh national meet of state biodiversity boards here.

Chennai Corporation had launched a programme to use plastic in laying roads.

The National Rural Roads Development Agency (NRRDA) has formulated guidelines for the use of plastic waste in rural roads construction. With the help of research carried by Prof. Vasudevan, Prof. Justo and Prof. Veeraragavan at Bangalore University and research carried out by Scientist at CRRI, New Delhi, NRRDA has built several trial roads using waste plastic.  

Such roads, popularly known as Plastic Roads, are found to perform better compared to those constructed with conventional bitumen. Further it has been found that such roads were not subjected to stripping when come in contact with water. With the experience gained over the years of construction of roads using waste plastic, CRRI as well as TCE have firmed up the specifications for the use of waste plastic and shared the specifications with organizations willing to construct the roads with waste plastic.

The guidelines were formed based on the presentations made by Dr. Sangita, Sr. Scientist, Flexible Pavement Division, CRRI and the literature supplied by Dr. R. Vasudevan.

Types of waste plastic, which can be used in the construction of rural roads can be classified as films, carry bags, cups, hard foams, soft foams, laminated plastics and packing materials used for biscuits, chocolates, etc.

Method of road laying

Dry process is recommended for isolated works. It is recommended that the percentage of shredded waste plastic will be 8% by Central Road Research Institute (CRRI), while the same is specified as 10% by Dr. Vasudevan. However we can adopt 8% as the optimum plastic content for blending the bitumen in the construction of plastic roads. The details of the process are given below. Bitumen of grades 60/70 or 80/100 can be used as binder as in case of conventional method, NRRDA said in a report.

With mini hot mix plant

 

The stone aggregate mix (as per specification) is transferred to the mix cylinder where it is heated to 165⁰c (as per the IRC specification) and then it is transferred to the mixing puddler(Temperature can be monitored using IR thermometer), while transferring the hot aggregate into the puddler, calculated quantity of shredded plastics is sprayed over the hot aggregate within 30seconds. The sprayed plastic films melts and gets coated over the aggregate, thus forming an oily coating.

Similarly, the bitumen is to be heated to a maximum of 160⁰c in a separate chamber and kept ready (The temperature should be monitored to have good binding and to prevent weak bonding).

At the mixing puddler, the hot bitumen is added over the plastic coated aggregate and the resulted mix is used for road construction. The road laying temperature is between 110⁰c to 120⁰c. The roller used is normal 8-ton capacity.

Advantages of plastic roads

·          

A well constructed plastic tar road will result in the following advantages.

·         Strength of the road increased (Increased  Marshall Stability Value)

·         Better resistance to water and water stagnation

·         No stripping and have no potholes.

·         Increased binding and better bonding of the mix.

·         Increased load withstanding property( Withstanding increased load transport)

·         Overall consumption of bitumen decreases.

·         Reduction in pores in aggregate and hence less rutting and raveling.

·         Better soundness property.

·         Maintenance cost of the road is almost nil.

·         The Road life period is substantially increased.

·         No leaching of plastics.