Recycling Plastic Waste to Build Roads
Most of the developing countries in the world face these two major issues – first the management of solid waste especially used plastic and second roads which either don’t exist or are full of potholes.
Plastic as we all know is non-biodegradable and is still excessively used for packaging. It has become an integral part of our everyday living obviously because it is easy to use, durable, light weight, easy to produce, odourless, has chemical resistance and is unbreakable.
Waste Plastic is a Huge Pollutant
In both urban and rural areas plastic in form of empty bags, bottles, foam etc. litters the roads, drains and pollutes water bodies. Many animals choke after consuming plastic bags from garbage and street side. It is also known to block germination in fields and prevent natural rainwater absorption which reduces our ground water table. In India plastic constitutes 5% in municipal solid waste. Even though plastic can be recycled 3-4 times, the melting process involved in this recycling produces highly toxic gases.
Many rural areas in developing countries are still not connected with solid roads. In cities and towns even though the roads are built regularly due to excessive traffic movement and poor quality of construction they are in bad shape.
Putting This Waste Plastic to Use
To deal with this problem many experiments have been performed over the years to put this widely used material ‘plastic’ to better ‘reuse’. Today it can be used to construct roads by mixing waste plastic with aggregate and bitumen. These roads are not only value for money and reuse plastic waste but are found to have more strength, higher resistance to water, higher skid resistance and high performing over a period of time compared to the conventional bitumen roads. Many developing countries like India, Ghana are using this technology to build roads in rural areas.
Except Poly Vinyl Chloride (PVC) sheets or Flux sheets most of the plastic types are suitable for such road construction. Plastics that are normally preferred for this process include – Films like Carry Bags, Cups with thickness up to 60 micron, hard foams of any thickness, Soft Foams of any thickness and laminated Plastics thickness of up to 60 micron including Aluminium coated packing materials used for biscuits, chocolates, etc. Most of these plastic forms are used by us on daily basis in our house and office. Plastic waste used should be free from dust and should preferably shed into 2-3 mm particle size.
The Road Laying Process
The process of laying these roads is simple and doesn’t require any new machinery or industry involvement. Firstly, plastic waste like bottles, bags, cups, biscuit and wafer packets etc.) made out of PE, PP and PS type of plastic is segregated, cleaned and then put in a shredding machine and cut to required size between 2.36mm and 4.75mm.
Then the aggregate is then transferred to chamber Aggregate heater and heated to 165°C and then transferred to a mixing chamber. At the same time bitumen is also heated up to a maximum of 160°C. Temperature monitoring is important as this gives bitumen good binding and prevents weak bond.
The third step requires mixing of hot aggregate with shredded plastic waste. The plastic gets uniformly coated over the aggregate within a matter of a minute and gives aggregate an oily look. The last step involves mixing of hot bitumen with the plastic coated aggregate mix. This is the end mix which is used to construct roads using an 8 tonne capacity roller. The resultant mix is at the temperature between 110°C to 120°C
By following these steps plastic roads can be easily constructed by normal labourers who make roads by using the same machinery and techniques they know. Rural areas in developing countries will benefit the most out of plastic roads as the reduced cost of laying these roads will make government connect rural homes with solid roads hence making them more accessible and dust free.
These environment friendly roads if well-constructed have many advantages over a conventional bitumen road. They use less percentage of bitumen and have higher road strength with higher load withstand property. With better water resistance plastic roads have less water stagnation and stay without potholes for a longer time. Maintenance cost of these roads is much less then bitumen roads and also they have longer life hence they are apt for far off areas like villages and small hill towns with under 100 homes. Also, plastic roads have no effect of radiation like UV.
Plastic waste is one of the biggest issues our environment faces today. Good connectivity is one of the biggest strengths a country can have. The technology of plastic roads deals with both these issues beautifully and should be used more extensively in road construction all over the world. The entire process of making plastic roads is not only simple and eco-friendly but is also feasible in long run.