Page 16 - U4SSC Case study: City solid waste management, June 2020

Promoting circularity

Vision and content

Plastic garbage is a common sight around the country and has started to cause numerous problems.
For instance, plastic waste clogs drains, causing floods. It also represents a choking hazard for animals
that eat plastic bags and similar items. Moreover, plastics found in fields block germination and prevent
rainwater absorption. Plastic waste also causes significant water pollution.

Recycling plastic can be done only 3–4 times and melting the plastic for recycling releases highly toxic
fumes. In India, plastic waste is recycled inefficiently. About 60 per cent of the plastic waste collected
and segregated gets recycled back into materials for further processing into consumer products, while
the remaining 40 per cent is left unutilized. This remaining plastic waste needs to be handled effectively
in order to protect the environment.

The plastic waste can be used in road construction. Field tests have proved that after proper processing,
plastic waste can be used as an additive to toughen roads while also helping to save the environment.
Plastic increases the melting point of the bitumen. A city using this technique for road construction and
maintenance is bound to benefit socially, economically and environmentally. Consequently, it should
be a part of any long-term city smart vision and strategy.

Implementation

Using recycled plastic to build roads has already been done in different parts of India, starting from
Tamil Nadu. The idea is gaining traction worldwide and is being tried out in countries like Uganda.

In India, which has a heavy rainfall during the monsoon season, the usual bitumen used in laying roads
is lost when rainwater penetrates underneath the layer and strips it from the binding layers below.
When plastic is used to coat the bitumen, it prevents water from seeping in. The road layer, therefore,
remains strong even after lashing rain.

Key features and design

The technology for this was developed by the ‘Plastic Man’ of India, Dr Rajagopalan Vasudevan,
Professor of Chemistry at Thiagarajara College of Engineering, Madurai, India. It promises to make a
significant difference to the quality of roads in India.

The process begins with the sorting of plastic waste, the shredding of the waste into tiny pieces,
roughly 2–4 mm in length, and by adding the shredded polymer waste to stone aggregate. The stone
aggregate, which is comprised of granite and ceramic pieces, is heated to 160–170° C. The coated
stone aggregate is then added to bitumen at a temperature between 155° and 163° C, and the mass
is mixed thoroughly. This mixture is then loaded onto road layers that put the final coat on the road.
It is finally levelled with a roller.

10 Case study: City solid waste management, June 2020