Today, we all now understand the role we need to play in reducing waste. This is particularly true when it comes to plastic waste. We also all appreciate that continually depleting our oil reserves to create new plastic is not sustainable. As such, we need to find ways to reuse and recycle our plastic waste. Here we look at an innovative solution, how about using plastic waste in road construction?
Supply and demand are two reasons why we consume and waste so much plastic. Consumers are purchasing more which increases manufacturing, and waste plastic keeps mounting up. The equation is simple, but the sums don't add up because the outcome is irreversible damage to our planet.
Oceans are awash with plastic bags and debris. Beaches are covered with washed-up and discarded plastic. The problem is massive. And it doesn't just impact us humans, it affects marine life too.
As awareness grows and new applications come to market, such as producing paving blocks from post consumer plastics, we begin to realize that our waste could, in fact, be rather useful to us.
We are living in a world that is constantly growing. The population is growing, and the need for more housing comes with that2. We also need new infrastructure with roads and pavements. And, of course, current roads and pavements need repairing and replacing.
Creating or replacing all of this is labor-intensive. New roads and buildings use natural resources such as aggregate (for cement), metal and wood, as well as other materials. Each of these conventional materials has some polluting qualities from mining, transportation, or manufacturing.
Yet, what if we were to reuse plastic waste that we had already produced? By marrying the near-endless need for materials for new roads and developments with the sheer volume of plastic waste, we generate, we have a solution - plastic paving.
It is now possible to contribute to the supply and demand of our paving needs with plastic paving4. When we use recycled plastic waste, we almost create a win-win situation.
What makes plastic paving so appealing is the way it reduces plastic waste1. So much of the plastic we use goes to waste. Much of it makes its way into waterways, and we fail to recycle much of it.
Along with this, the process of recycling plastic into high-grade applications (e.g. food packaging) is time-consuming and costly. Further, the lifecycle of this plastic continues as it will only be put back into use where it could once again become discarded waste.
So, when we incorporate plastic waste into paving, we reduce the amount that ends up being discarded.
You only have to look at how long plastic takes to break down to realize how strong it is. We are talking hundreds of years for it to disappear. Even then, it never entirely leaves the environment.
This is because it does not get broken down by organisms. Its durability and the materials we use to make it are solid and highly (re)usable. When we look at concrete, it can crack and break. Asphalt used for roads has a lifespan of around 15 years, while concrete lasts around 25 years.
Of course, standard asphalt concrete roads asphalt might be cheaper than plastic paving until production scales up and costs come down. However, the durability of plastic paving will certainly make it more cost-effective in the long run.
While many different non-renewable sources go into making plastic, once we have made it and can reuse it, we no longer have to use these resources again.
Further, by reusing plastic material to create paving, we can make resource savings elsewhere. Making asphalt and concrete is harmful to our environment in many ways.
First, we have to mine the materials, much of which come from quarries. It has to be transported and added to other materials before being manufactured. The manufacturing process alone creates greenhouse gases. Adding plastic to asphalt allows for a lower working temperature which means less energy consumption during production.
So, when we recycle plastic waste and turn it into plastic paving, we prevent environmental harm by drawing on a new resource.
Flooding is a huge concern for the modern world. Rainfall is increasing and so are large-scale developments that prevent natural run-off. This means that we are removing soil that would soak up the rain and replacing it with cement, concrete, and tarmac that hold water and causes it to run into rivers and lakes.
In contrast to this, plastic paving can help to remove rainwater. Plastic paving can have hidden run-off channels below the surface. This can help to channel water and direct it correctly to run-off areas.
All of this can help to prevent flooding. And many drivers will support its durability resulting in fewer potholes.
The process of making paving blocks from plastic is one that can be done both commercially and as a DIY process.
As it currently stands, plastic waste is being used as an additive in the process. As such, they are making roads utilizing a blend of shredded plastic waste and bitumen in India3. In Bali, they reuse the plastic waste in an asphalt mix.
The roads are created by blending different types of recycled plastic waste. First, the process begins with collecting plastic waste. This consists mainly of consumer waste such as product packaging. As a result, the most common forms of plastic are Polyethylene Terephthalate (PET or PETE), polypropylene (PP), and high and low-density polyethylene (HDPE and LDPE).
The materials go through a sorting process. They then go through the process of being cleaned and dried before going through a shredder. The shredded material is melted before bitumen or asphalt is added to the mix.
While plastic roads or paving have not been used on a large scale, things are progressing in the Netherlands. The aim is to create 100% plastic roads. They predict these will last three times longer, construction is 70% faster, and it is possible to recycle the road when the time comes to replace it.
What's more, making your own plastic paving is possible.
To begin with, you need to make sure that you have the right plastic. This involves plastic bags and other plastics made from the materials mentioned above. They can be placed in a metal barrel and then placed on a source of heat.
Once the mixture melts, it can be poured into an oiled mold and mixed with sand. It is also possible to pour it into the mold with no additives.
Waste is a significant problem in Cameroon. As a result, entrepreneur Pierre Lasoumloum is helping to deal with the situation. This initiative uses waste as a binding agent to create paving slabs.
By involving the local community, he has gained a lot of attention, training up local children who might have otherwise spent their time on the streets to assist with the process. As a result, he has received funding from the 'Coeur d'Afrique.' He has provided paving stones to the Cameroon handball federation and also raises awareness of plastic waste in schools.
Elsewhere in the Netherlands, PlasticRoad is an initiative to make roads completely from plastic. Currently, trials are being conducted in Zwolle, and the results look promising.
The idea is that the parts are prefabricated and modular. The structure is light and hollow, and that enables fast construction and replacement. The hollow design helps with flooding and the installation of pipes and cabling.
What's more, it is a circular economy product. This means that we can reuse and recycle it time and time again, unlike traditional road construction. Along with this, the carbon footprint is much smaller than conventional road construction materials.
Prevention is better than cure, as they say. Therefore, plastic paving could be a great way of preventing plastic waste from polluting our environment. Whether waste plastics are used as a binding agent or used on their own to make roads, it is a potential game-changer.
The amount of roads and pavements we create or repair is staggering. Therefore, utilizing plastic waste as paving slabs or roads could make a significant impact. This is no doubt a positive step in the right direction when it comes to our fight to reduce plastic waste.
|Zhen Leng, Rabindra Kumar Padhan, Anand Sreeram, Production of a sustainable paving material through chemical recycling of waste PET into crumb rubber modified asphalt, Journal of Cleaner Production, Volume 180, 2018, Pages 682-688, ISSN 0959-6526, https://doi.org/10.1016/j.jclepro.2018.01.171|
|Dowell Myers, John Pitkin & Julie Park (2002) Estimation of housing needs amid population growth and change, Housing Policy Debate, 13:3, 567-596, DOI: 10.1080/10511482.2002.9521455|
Plastic Roads - Use of Waste Plastic in Road Construction (pdf), Ahmed Trimbakwala, Department of Civil Engineering, K. K. Wagh Polytechnic, Nashik
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