Investigating the Effects of Adding Polyethylene Terephthalate (PET) on Asphalt Mixes Performance

Abstract

Plastic bottles are one of the most widely used and mass-produced items whose production is increasing day by day. Non-biodegradable waste plastic remains in the environment and adversely affects the ecological system. Combustion of this waste is also not a feasible idea as the process releases toxic gases into the atmosphere which are destructive to human life. The resultant emission of CO2, a primary greenhouse gas, is of huge concern to the environmentalists and the world community alike. Pakistan is directly taking the blunt of this environmental problem due to the lack of proper waste disposal mechanism and the ever-growing population. Shredding waste plastic bottles into small sized pieces and subsequently mixing with aggregate or binder is possible. This study tackles this idea of using waste plastic bottles to enhance the properties of bitumen individually, increase the strength and durability as a bituminous mixture and subsequently reducing the impact of waste plastics on the environment. Bitumen is modified with the shredded pieces of waste plastic (PET) and tests were performed on the samples consisting of 6%, 8%, 10% and 12% PET by weight of bitumen. Test results marked an increasing trend in Softening, Flash and Fire Point, Marshall Stability with increasing percentages of PET. The Softening point increased from 49 ⁰C at 0% PET to 56 ⁰C at 12% PET. Similarly, Flash point increased from 276 ⁰C to 294 ⁰C, Fire point increased from 282 ⁰C to 300 ⁰C, and Marshal Stability from 1133.5 kg to 2018.5 kg. Marshall Flow values followed a different trend, it increased till 10% PET addition but started decreasing from 12% addition of PET. Whereas, a decrease in penetration value and ductility of the mixture was noted. Penetration value decreased from 60 to 45.4 and ductility decreased from 116 mm to 87 mm.