Chemistry:Plastic roads

Plastic roads are made entirely of plastic or of composites of plastic with other materials. Plastic roads are different from standard roads in the respect that standard roads are made from asphalt concrete, which consists of mineral aggregates and asphalt.

Classification

There are two kinds of Plastic roads:

• the "PlasticRoad": consist of modular, hollow and prefabricated road elements made from consumer waste plastics, and
• Plastic Roads: consist of an asphalt mix with plastic waste incorporated into the asphalt mixture.

Plastic roads

First recycled glass and plastic road in New South Wales, Australia at suburb Engadine

Plastic roads first developed by Rajagopalan Vasudevan in 2001, consist of an asphalt mix with plastic waste incorporated into the asphalt mixture. The implementation of plastics in roads also opens a new option for recycling post consumer plastics. Australia , Indonesia, India , the United Kingdom , the United States , and many other countries have used technology which can incorporate plastic waste into an asphalt mix.

PlasticRoad

In the Netherlands in the cities of Zwolle and Giethoorn there are two bicycle paths installed made purely from waste plastics. This is the result of an collaboration between three companies: VolkerWessels, Wavin and Total. The "PlasticRoad" cannot be compared with normal plastic roads. The "PlasticRoad" built by the three companies consists of prefabricated, hollow, modular elements made from consumer waste plastics, and is a unique innovation all over the world. The original idea for the PlasticRoad was invented by Simon Jorritsma and Anne Koudstaal but was inspired from the work that was being carried out in India. In 2015, the PlasticRoad concept was presented to the world with the goal of finding partners to bring the idea to reality The PlasticRoad has a lot of advantages compared to normal roads, including hollow space for the storage of excessive rainwater, the light weight, and the sustainability benefits.

Initial Development

The technology was initially developed and patented by Rajagopalan Vasudevan of the Thiagarajar College of Engineering. He developed an innovative method to reuse plastic waste to construct better, more durable and very cost-effective roads. This method will help in making roads much faster and also will save the environment from dangerous plastic waste. The roads also show greater resistance to damages caused by heavy rains. In an interview with The Better India, he explained, “The advantages of using waste plastics for road construction are many. The process is easy and does not need any new machinery. For every kilo of stone, 50 gms of bitumen are used and 1/10th of this is plastic waste; this reduces the amount of bitumen being used.  Plastic increases the aggregate impact value and improves the quality of flexible pavements.  Wear and tear of the roads has decreased to a large extent.”

The plastic-bitumen road-laying technique covered under a patent held by the Thiagarajar College of Engineering in 2006. Dr Vasudevan has since made it free to use for the greater good. The technology is simple and is described in a dedicated TCE website.

It involves

a) collecting waste plastics, including plastic carry bags, cups, soft and hard foams, and laminated plastics;

b) cleaning it by washing;

c) shredding it to a uniform size;

d) melting the waste plastics at 165 °C, and blending it with hot aggregates and bitumen and using this mixture to lay the road.

Construction

Since plastic roads are a relatively new idea, construction processes vary. In Jamshedpur, India, roads are created from a mix of plastic and bitumen. In Indonesia roads are also being built using a plastic-asphalt mix in many areas including Bali, Surabaya, Bekasi, Makassar, Solo, and Tangerang.

These roads are made from recycled plastics, and the first step in constructing them is to collect and manage the plastic material. The plastics involved in building these roads consists mainly of common post-consumer products such as product packaging. Some of the most common plastics used in packaging are polyethylene terephthalate (PET or PETE), polypropylene (PP), and high- and low-density polyethylene (HDPE and LDPE). These materials are first sorted from plastic waste. After sorting, the material is cleaned, dried, and shredded. The shredded plastic is mixed and melted at around 170 °C. Hot bitumen is then added and mixed with the melted plastic. After mixing the mixture is laid as one would with regular asphalt concrete.

So far, no large-scale, systematic approach has been employed to build roads entirely of plastics in Netherlands. On September 13, 2018, the Dutch company Volkerwessels built a bicycle path made of recycled plastic in Zwolle, in the northeast part of the Netherlands. According to the Guardian, "A second path is to be installed in Giethoorn in Overijssel, and Rotterdam is the city most likely to take up the technology."

Usage by country

India

Chennai was among the first cities globally to adapt the technology in a big way when the municipality commissioned 1000 km of plastic roads in 2004. Since then all major municipalities in India have experimented with the technology including Pune, Mumbai , Surat, Indore, Delhi, Lucknow etc.

Chennai: While the plastic roads may be a new concept in many parts of India, Chennai has been experimenting with it since 2011. Chennai has used nearly 1,600 tonnes of plastic waste to construct 1,035.23 kilometres length of roads in recent years, which include N.S.C Bose road, Halls road, Ethiraj Silai Street and Sardar Patel Street.

Pune: Using bitumen technology on waste plastic, the Pune Municipal Corporation constructed a 150-metre stretch of Bhagwat lane at Navi Peth near Vaikunth Crematorium in 2016. The other trial patches in Pune include Dattawadi Kaka Halwai Lane, Katraj Dairy, Magarpatta City HCMTR Road, Kavde Mala Road, Koregaon Park Lane No 3 and Yeravada Sadal Baba Darga Road from Chandrama Chowk.

Jamshedpur: Jamshedpur Utility and Services Company (JUSCO), which is a subsidiary company of Tata Steel, constructed a 12-15 km road in the steel city as well as Tata Steel Works using plastic road, including a nearly 1 km stretch in Ranchi, 500m stretch each in Dhurwa and Morabadi, 3 km of roads in Chas and Jamtara each and 500m stretch in Giridih.

Indore: Dating 2014, the Madhya Pradesh Rural Road Development Authority (MPRRDA) has constructed around 35 km of roads in 17 districts with plastic waste.

Surat: The idea of using plastic-bitumen mix was executed in January 2017. The problem of potholes significantly reduced as no cracks developed in areas where roads were layered with waste plastic.

The technology has penetrated deeply and has found application even in far flung areas such as Meghalaya, where a village converted 430 kg of plastic waste into a kilometer long road in 2018.

In December 2019, India has built 21,000 miles of roads using plastic waste. Till now, the country has almost 33,700 km of plastic roadways that means every 1 km road uses 1 million plastic bags.

United Kingdom

In January 2019, the Department for Transport announced a £1.6 million UK trial of a plastic road technology developed by MacRebur, an asphalt enhancement company based in Scotland.

In MacRebur's process, anywhere between 3–10 kg of waste plastic is used in each ton of asphalt. The aim of the initiative is three-fold: to use the millions of tons of plastic waste currently sitting in UK landfills, to reduce the millions of pounds of government money spent on new roads, maintenance, and pothole repair, and to make roads stronger and longer-lasting.

MacRebur's technology includes the patent-pending MR6, MR8 and MR10, all of which use a carefully selected mixture of polymers, specifically designed to improve the strength and durability of asphalt and reduce the quantity of bitumen required in the mix. The polymers are made from 100% waste materials and are used in the making of both hot and warm mix asphalt. The method of manufacture for these polymers means they contain no microplastics.

Cumbria was the first council in the UK to use the patented asphalt enhancement. Since then, the polymers have also been laid in Dumfries and Galloway, Gloucester, London, Newcastle upon Tyne, Durham and in the Central Belt. As part of the project, research into the technology will be carried out by Gaist, as well as The University of Nottingham, University of Central Lancashire, University of the Sunshine Coast, in Australia and the University of California.

Pakistan

Pakistan generates at least 30 million tons of solid waste per year. Some sources claims this number is as high as 48 million tons, whereas it is estimated that solid waste generation is increasing by 2% to 3% per year. Out of this, 77 thousand tons per day is generated in main metropolitan areas whereas 70% to 80% of this waste is collected for proper disposal. According to the United Nations Development Program (UNDP) environment project report on solid waste management published in 2016, Pakistan's plastic waste is at fourth position amongst all solid waste collected.

Pertinently, Pakistan imported approximately USD 76 million worth of Bitumen in 2018. Thus, the use of plastic waste of roads pavement provides opportunity for significant import substitution, and result in substantial savings of foreign exchange. The Payment details on imports made in US Dollar for Bitumen during the year 2018 was PKR 11,959,315,712 and in USD 76,248,509 against the 195,509 metric tons. At least 10% was possible as direct saving whereas the same saving rate is possible to achieve due to more stronger constructions mix of roads.

Properties

Below are some of the advantages and disadvantages of plastic roads.

Advantages

• In the proposed model by Volkerwessels, plastic roads can have hollow space built in to allow ease of wiring, connecting pipes, etc.
• Since plastics come with various chemical and physical properties, roads can be engineered to meet specific requirements (e.g. weather and wear resistance)
• Plastic roads can be built from waste plastic --- the majority of which is usually put into landfill, incinerated, or polluted into the environment. Land-filling and incinerating plastic are both problematic methods of managing plastic waste. Plastics in landfills can leak pollutants into the surrounding soil; incinerating creates gaseous pollutants, such as carbon dioxide.
• Plastic-bitumen composite roads need not be especially discriminating with the plastics used, thus increasing the reuse of plastic. Most plastic waste is not recycled because it is usually mixed with different types of plastic and non-plastic (e.g. paper labels) and, so far, the segregation process is labor-intensive with no easy solution.
• Using less asphalt saves on cost and resources. Asphalt concrete requires petroleum which is becoming more scarce.
• The addition of plastic in asphalt can reduce the viscosity of the mix. This allows a lower working temperature, which lowers VOC and CO emissions.
• Plastic-bitumen composite roads have better wear resistance than standard asphalt concrete roads. They do not absorb water, have better flexibility which results in less rutting and less need for repair. Road surfaces remain smooth, are lower maintenance, and absorb sound better.

Disadvantages

• Pure plastic roads require use of compatible plastics because, when melted, plastics of different types may phase-separate and cause structural weaknesses, which can lead to premature failure.
• Plastics in the road can break down into microplastics and can find their way into the soil and bodies of water. These microplastics can also absorb other pollutants.
• Every time maintenance is performed on these modular roads the flow of power, water, and internet that has been installed within will be interrupted.