Using plastic wastes for laying roads is fast
catching up among Indian cities and Indian government is mulling to formulate national
level policy to use the technology on highways roads.
Though several cities in India have banned usage of
plastics, the disposal of a large quantity of non-biodegradable wastes being
accumulated daily has become a challenging task for the governments and a worrying
factor for environmentalists. Though re-cycling of plastics is addressing the issues
to certain extent, it’s still lot to done. Using waste plastic materials to lay
roads is a new concept, fast catching up in India.
Tamil Nadu has become a pioneer in using this
technology invented by Chemistry professor Vasudevan
of Thiagarajar College of Engineering in Madurai. Now, encouraged by the use of
plastic in road laying in Tamil Nadu, the Centre is mulling a national level
policy on its usage on national highways and other state highway roads. Mumbai
too has tested plastics on road laying and found it to be a viable solution for
frequent re-laying of roads after every monsoon.
"Using plastic in laying roads will increase the life of roads. We have to prepare a national level policy on this. We are talking over this," Environment and Forests Minister Jayanthi Natarajan told reporters on the sidelines of the seventh national meet of state biodiversity boards here.
Chennai Corporation had launched a programme to use plastic in laying roads.
"Using plastic in laying roads will increase the life of roads. We have to prepare a national level policy on this. We are talking over this," Environment and Forests Minister Jayanthi Natarajan told reporters on the sidelines of the seventh national meet of state biodiversity boards here.
Chennai Corporation had launched a programme to use plastic in laying roads.
The National Rural Roads
Development Agency (NRRDA) has formulated guidelines for
the use of plastic waste in rural roads construction. With the help of research
carried by Prof. Vasudevan, Prof. Justo and Prof. Veeraragavan at Bangalore
University and research carried out by Scientist at CRRI, New Delhi, NRRDA has
built several trial roads using waste plastic.
Such roads, popularly known as Plastic Roads, are found to
perform better compared to those constructed with conventional bitumen. Further
it has been found that such roads were not subjected to stripping when come in
contact with water. With the experience gained over the years of construction
of roads using waste plastic, CRRI as well as TCE have firmed up the
specifications for the use of waste plastic and shared the specifications with
organizations willing to construct the roads with waste plastic.
The guidelines were formed based on the presentations
made by Dr. Sangita, Sr. Scientist, Flexible Pavement Division, CRRI and the
literature supplied by Dr. R. Vasudevan.
Types of waste plastic, which can be used in the
construction of rural roads can be classified as films, carry bags, cups, hard
foams, soft foams, laminated plastics and packing materials used for biscuits,
chocolates, etc.
Method of road laying
Dry process is recommended for isolated works. It is recommended that the percentage of shredded waste plastic
will be 8% by Central Road Research Institute (CRRI), while the same is
specified as 10% by Dr. Vasudevan. However we can adopt 8% as the optimum
plastic content for blending the bitumen in the construction of plastic roads.
The details of the process are given below. Bitumen of grades 60/70 or 80/100
can be used as binder as in case of conventional method, NRRDA said in a report.
With
mini hot mix plant
The
stone aggregate mix (as per specification) is transferred to the mix cylinder
where it is heated to 1650c (as per the IRC specification) and then
it is transferred to the mixing puddler(Temperature can be monitored using IR
thermometer), while transferring the hot aggregate into the puddler, calculated
quantity of shredded plastics is sprayed over the hot aggregate within
30seconds. The sprayed plastic films melts and gets coated over the aggregate,
thus forming an oily coating.
Similarly,
the bitumen is to be heated to a maximum of 1600c in a separate
chamber and kept ready (The temperature should be monitored to have good
binding and to prevent weak bonding).
At
the mixing puddler, the hot bitumen is added over the plastic coated aggregate
and the resulted mix is used for road construction. The road laying temperature
is between 1100c to 1200c. The roller used is normal
8-ton capacity.
Advantages of plastic roads
·
A well constructed plastic tar road will
result in the following advantages.
·
Strength of the road increased
(Increased Marshall Stability Value)
·
Better resistance to water and water
stagnation
·
No stripping and have no potholes.
·
Increased binding and better bonding
of the mix.
·
Increased load withstanding
property( Withstanding increased load transport)
·
Overall consumption of bitumen
decreases.
·
Reduction in pores in aggregate and
hence less rutting and raveling.
·
Better soundness property.
·
Maintenance cost of the road is
almost nil.
·
The Road life period is substantially
increased.
·
No leaching of plastics.