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A new technology developed by a team of entrepreneurs in Bangalore, Hyderabad, India use waste plastic for construction of roads.

Bangalore-based K K Polyflex, a firm manufacturing plastic goods, came up with the technology, which also addressed the problem of disposal of plastic waste in an environmental friendly manner.

The Centre for Transportation Engineering and Civil department of Bangalore University carried out tests on the possible use of the processed plastic bags as an additive in bituminous concrete mixes.

It has been possible to improve the performance of bituminous mixes used in the surfacing course of road pavements, with the help of various types of additives to bitumen such as polymers, rubber latex, crumb rubber- treated with some chemicals, and so forth.

English: Old, used asphalt-pavement.

English: Old, used asphalt-pavement. (Photo credit: Wikipedia)

Some limited studies have been reported on the use of re-cycled plastic, mainly polyethylene, in the manufacture of polymer – modified asphalt cement or bitumen. According to Larry Flynn (“Recycled Plastic Finds Home in Asphalt Binder”, Journal, Roads and Bridges, March 1993), re-cycled polyethylene from grocery bags may be useful in asphaltic (bituminous) pavements, resulting in reduced permanent deformation in the form of rutting and reduced low – temperature cracking of the pavement surfacing.

Salah E. Zoorob (“Laboratory Design and Investigation of Proportion of Bituminous Composite Containing Waste Recycled Plastics Aggregate Replacement (Plastiphalt), CIB Symposiumon Construction and Environment Theory into Practice, Sao Paulo, Brazil (November, 2000)) and Zoorob and Suparma (“Laboratory Design and Performance of Improved Bituminous Composites Utilising Plastics Packaging Waste”, Conference on Technology Watch and Innovation in Construction Industry, Belgium, Building Research Institute, Brussels, Belgium (April, 2000)) have shown that re-cycled plastics composed predominantly of polypropylene and Low Density Polyethylene can be incorporated into conventional asphaltic (bituminous) road surfacing mixtures.

Greater durability and fatigue life have been reported in these modified mixes as compared to conventional mixes.

The processed plastic was used as an additive with heated bitumen in different proportions (ranging from zero to 12 % by weight of bitumen) and mixed well by hand, to obtain the modified bitumen.

The properties of the modified bitumen were compared with ordinary bitumen. It was observed that the penetration and ductility values of the modified bitumen decreased with the increase in proportion of the plastic additive, up to 12 % by weight.

Studies were carried out on Bituminous Concrete (BC) mixes using 80 / 100 grade bitumen having average Marshall Stability Value (MSV) of 1100 kg at optimum bitumen content of 5.0 % by weight of the mix.

Further studies on BC mixes were carried out using the modified binder obtained by the addition of varying proportions of processed plastic bags (percentage by weight of bitumen) with the conventional 80 /100 grade bitumen.

The optimum modified binder content fulfilling the Marshall mix design criteria was found to be 5.0 % by weight of the mix, consisting of 8.0 % by weight of processed plastic added to the bitumen.

The average MSV of the BC mix using the modified binder was found to be as high as 3312 kg at this optimum binder content, resulting in about three fold increase in stability of the BC mix, which contains 4.6 % bitumen plus 8 % processed plastic by weight of bitumen, i.e., 0.4 % processed plastic by weight of the mix.

The laboratory investigations carried out at Bangalore University have given highly encouraging results for the use of bituminous concrete mixes in the surfacing course of road pavements by using this modified binder which is prepared by the addition of 8.0 % of the processed plastic, by weight of bitumen. 3.2. Advantages of Using Modified Bitumen with Processed Plastic as Additive.

Pointing out that the universities have given their certification to this new method, the chief minister of Hyderabad said the government should not have any problem in utilising it.

Waste plastic proved to be good for construction of road as it increases the life of roads three-fold. This apart, the frequency of road repairs would be reduced as the chances of seepage of rain water is minimised due to presence of plastic.

However, the cost of road construction was slightly higher compared to the conventional method. This should not deter the adoption of the technology as the benefits are much higher than the cost.

Source : Utilisation of Waste Plastic Bags in Bituminous Mix for  Improved Performance of Roads, Centre for Transportation Engineering, Bangalore University, Bangalore, India, 2002 and http://www.mindfully.org

(this article written for 1BINA.my)

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