A scientific and technical background on Green roads
Waste plastic mixed with bitumen results in construction material with enhanced properties that improves the road life and reduce the need for maintenance.
The main steps that are followed while construction of Greener Roads are:
Collection: Collection of plastic wastes from community or industrial waste streams.
Cleaning: Cleaning of plastics if they were mixed with wastes that cannot be processed. (If proper waste segregation and waste auditing is done, this labor intensive process is not required.)
Shredding: Plastic wastes are shredded to a suitable size needed to utilize for road construction.
Processing: The shredded plastics are heated up and mixed with aggregates before adding bitumen so as to increase surface properties like binding and water resistance.
Paving: The roads are now ready to pave! Without the use of any extra machinery and in a foolproof and greener way.
These roads withstand loads due to heavy traffic, rain and temperature variation. But, the employment of plastic waste as modifier is successful only if it coats the aggregate well and the aggregate becomes non‐wetting with enhanced mechanical properties like enhancement of useful properties like strength, stability, longevity and durability of roads. The Green Roads are designed particularly for benefits like protection from weather erosion, considerably reduction in the cost of the constructed road component and reduction in initial cost and maintenance requirements of roads. In order to check for the inclusion of plastic in the aggregate bitumen mix, various characterization techniques have been used and tested in labs and are listed here:
- Stripping test (IS: 6241‐1971)
- Los Angeles Abrasion Test
- Aggregate Crushing Test
- Aggregate Impact Test
- Marshall Stability Test
- Water absorption test
- Extraction of bitumen Test
The result obtained for plastic coated aggregate turned out to be the best in all of the above tests conducted in the lab. The practical experience from the plastic roads built in foreign countries, we learnt that the durability of the roads are higher than ordinary roads.
Where have we successfully constructed roads:
Length: 100 meters
Width : 6 meters
Thickness : 20 mm
Date : June 2018
Amount of plastic used : 300 kgs
Amount of Bitumen saved : 250 kgs
Reduced carbon emission by : 900 kgs
Length of the road: 200 meters
Width of the road : 6 meters
Thickness of the road : 40 mm
Date : April 2019
Amount of plastics used : 750 kgs
Amount of Bitumen saved : 600 kgs
Reduced carbon emission by : 2000 kgs