of plastics coating over aggregate Compression Strength ( Tonnes) Bending Strength (Kg)
10 250 325
20 270 335
25 290 350
30 320 390
The increase in the values of the compression strength and bending strength shows that the plastics can be used as a binder.
CONCEPT OF UTILISATION OF WASTE PLASTIC IN
BITUMINOUS MIXES FOR ROAD CONSTRUCTION:
This Concept of Utilization of Waste Plastic in Bituminous Mixes for Road Construction has been done since 2000 in India, They can return to the earth as beneficial additives in bitumen roads. One such technologies are reviewed below, two for waste-polymer-modified bitumen roads.
BANGALORE'S KK PROCESS:-
At the initiative of M/s K.K. Poly Flex Pvt. Ltd., a study on the possible use of the processed plastic waste bags with the bituminous mixes was carried out at the R.V. College of Engineering Bangalore. A group of students of B.E. degree course in Chemical Engineering of this college under the guidance of the concerned teaching staff carried out their final year project work for studying the possibility of using of the processed plastic bags with bitumen and bituminous mixes. As some encouraging results were reported in this study, M/s K.K. Poly Flex Pvt. Ltd. later approached the Centre for Transportation Engineering of Bangalore University with the request to carry out further research studies on the effects of using the processed plastic bags with bituminous mixes for road construction works.
In practice, such a "plastic road" laid in Bangalore (at the busy Rajarajeshwari Junction) in March 2001 as a technology demonstration for the Chief Minister, showed superior smoothness and uniformity and less rutting as compared to a plastics-free road laid at the same time, which has begun to develop "crocodile cracks". As a result, by now 25 km of "plastic roads" have been laid in Bangalore, unfortunately without another same-day plastics-free normal road. All these 25 km are performing well. The process was also approved in 2003 by the CRRI=Central Road Research Institute Delhi, and has thereafter been included in the Govt of Karnataka's PWD Schedule of Rates. Road life improves through improved tackiness and viscosity of the bituminous mix, thereby binding the stones more firmly together and improving the water-resistance of the mix to rain etc. For the same reason, the temperature of the mix both at the plant and at the point of lying needs to be 20°C higher than normal.
The Bruhat Bengaluru Mahanagara Palike (BBMP) has used plastic on about 600 km of roads, including many thoroughfares and arterial roads. It uses the plastic blend in at least 25% of the road-laying works, including the present project to upgrade about 45 roads in the city. The plastic model was successful on major roads in Bangalore, including
Shankar Mutt Road, K H Road, M G Road (towards Trinity Circle), J C Nagar Road, Miller's Road and Cunningham Road. The rise in bitumen costs over the past few years has also made the plastic model more cost-efficient. To top it, plastic is not recycled but buried with the roads, forever.
Aggregate of 20mm, 10 mm. Stone Dust and Lime as Filler
• 60/70,80/100grade bitumen
Waste plastic in the shredded form
i. collection of waste plastic
ii. cleaning and shredding of waste plastic
iii. mixing of shredded waste plastic, aggregate and bitumen in
central mixing plant
iv. laying of bituminous mix
a. COLLECTION OF WASTE PLASTIC:-
Waste plastic is collected from roads, garbage trucks, dumpsites or compost plants, or from school collection programs, or by purchase from rag-pickers or waste-buyers at Rs 5-6 per kg
b. CLEANING AND SHREDDING OF WASTE PLASTIC:-
Waste plastic litter in the form of thin-film carry-bags, use-and-throw cups, PET bottles, etc. these are sorted, de-dusted, washed if necessary.
Fig. cleaning process Plastic waste which is cleaned is cut into a size between 1.18mm using shredding machine as shown below
c. MIXING OF SHREDDED WASTE PLASTIC, AGGREGATE AND BITUMIN IN CENTRAL MIXING PLANT:-
The aggregate mix is heated to 1650c (as per the HRS specification) in central mixing p