Hyderabad: For a safer disposal of plastic, Ministry of Road Transport and Highways has decided to encourage the use of plastic waste in the construction of National Highways.
The Ministry of Road Transport and Highways has issued guidelines for its use within 50 km periphery of urban areas having a population of more than 5 lakh. The guidelines also stipulate taking up of a stretch of at least 10 km as pilot project for assessment of its performance.
In an order issued by Ministry of Road Transport and Highways to State governments recently, it said that heating of plastic waste beyond 180 degree Celsius can thermally degrade the plastic and lead to emission of harmful gases. As such, maintenance of appropriate temperature is quite essential for successful implementation of use of plastic waste for highways construction.
“Use of plastic waste should be 8 per cent by weight of bitumen. However, addition of plastic wastes should not be considered as replacement of bitumen by same percentage from the bituminous mix of wearing course,” the order said.
The bituminous or asphalt mix using plastic waste will be designed as per the Ministry’s specifications and based on such design formulation, the percentage of bitumen and plastic waste has to be used.
Plastic waste has already been utilised in wearing course of about 50 km of National Highway stretches. The Indian Roads Congress (IRC) has formulated IRC SP: 98:2013 ‘Guidelines for the use of plastic waste in hot bituminous mixes (dry process) in wearing courses’ based on laboratory as well as field performance studies/investigations carried out in India.
According to IRC, the process include collection of plastic waste, cleaning and shredding of plastic waste, mixing of shredded plastic waste, aggregate and bitumen in central mixing plant and laying of asphalt mix.
Being a non-biodegradable material, plastic does not decay over time and even if dumped in landfills, it finds its way back in the environment through air and water erosion, which choke the drains and drainage channels.
For this, IRC found out that the best way of disposal of plastic waste is its recycling to the maximum extent, and many developed countries have recycled plastic waste to manufacture various products, including in heavy construction.
There are two processes namely dry process and wet process for manufacturing asphalt mixes using plastic waste. In the dry process, processed plastic waste is added after shredding in hot aggregates where as in the wet process, processed plastic waste in the form of powder is added in the hot bitumen.