1. Construction

2. Use in the UK

3. Properties
     Pros    Cons  

4. References

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.^[3] In Indonesia roads are also being built using a plastic-asphalt mix in many areas including Bali, Surabaya, Bekasi, Makassar, Solo, and Tangerang.^[4]

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), polyvinyl chloride (PVC), polypropylene (PP), and high and low density polyethylene (HDPE and LDPE).^[3][9] 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.^[5] 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. On September 13, 2018, the Dutch company Volkerwessels built a bicycle path made of recycled plastic in Zwolle, in the North-east 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." ^[6][7]

Use in the UK

In January 2019, The Department of Transport announced a £1.6 million UK trial of a plastic road technology developed by MacRebur, an asphalt enhancement company based in Scotland.^[8]

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.^[9]

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.{{Citation needed|date=April 2019}}

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.{{Citation needed|date=April 2019}}

Properties

Below are some of the pros and cons of plastic roads.

Pros

• In the proposed model by Volkerwessels, plastic roads can have hollow space built in to allow ease of wiring, connecting pipes, etc.^[7]
• 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. Landfilling 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.^[10]
• 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. ^[10]
• Using less asphalt saves on cost and resources. Asphalt concrete requires petroleum which is becoming more scarce.^[1][11]
• 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.^[12]
• 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.^[13]

Cons

• 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.^[14]

• Plastics in the road can break down into microplastics and can find their way into the soil and waterways. These microplastics can also absorb other pollutants.^[15]

References

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