In a perfect world, roads would not exist and therefore neither bitumen nor bitumen enhanced with plastic would be required. However, since 90 percent of the world’s roads are paved with bitumen, it behooves us to compare bitumen-only roads with bitumen-and-plastic rather than fantasizing about perfection.
And Plastic Roads are better than conventional roads. There are hundreds of studies leading to this conclusion.
| Nouali, M. et al (03 Jan 2019) “Plastic bag waste modified bitumen a possible solution to the Algerian road pavements.” Road Materials and Pavement Design. 09 Sept 2019 from https://www.tandfonline.com/doi/full/10.1080/14680629.2018.1560355/
“This study examines the suitability of using plastic bag waste as a bitumen modifier in order to improve the behaviour of asphalt mixes. This paper analyses the effect of adding plastic bag waste; low density polyethylene (LDPE), to a conventional 40/50 graded bitumen. Basic rheological parameters such as penetration, softening point, ageing (RTFOT) and storage stability were used to determine the plastic addition resulting changes on the modified bitumen, expressed relatively to the pure bitumen basis. FTIR spectroscopy was also used to study the chemical functionalities present in the modified bitumen. It was observed that the penetrability of the waste plastic modified bitumen (WPmB) decreases and its softening point increases. Consequently, its thermal susceptibility and its aging rate decrease. Performances of the WPmB were then determined on an asphalt concrete mix (AC) in terms of mix compaction behaviour, stiffness modulus and water resistance ameliorations. Results obtained show that adding plastic waste to the pure bitumen allows reducing void content of the mix and increasing substantially its stiffness modulus and water resistance.“
| White, G. et al (2018) “RECYCLED WASTE PLASTIC FOR EXTENDING AND MODIFYING ASPHALT BINDERS” Paper presented at the 8th Symposium on Pavement Surface Characteristics: SURF 2018 – Vehicle to Road Connectivity, Brisbane, Queensland, 2018. 09 Sept 2019 from https://trid.trb.org/view/1538158
“Plastic drink bottles, single-use plastic bags and other waste plastics have a significant impact on the environment. Consequently, there is global interest in recycling and reuse of waste plastics. Significant progress has been made towards the incorporation of waste plastics into building and construction materials, although this has focussed [sic] mainly on cement and concrete applications. This paper assesses the use of three commercially available recycled plastic products for bituminous binder extension and modification in asphalt mixtures. Using a dry-mixing process, shredded and pelletised recycled waste plastics replace 6% of the binder volume. Comparative laboratory testing of two typical UK asphalt mixtures indicated that asphalt containing the recycled waste plastic products showed improved deformation resistance and fracture resistance compared to conventional 40/60 penetration grade binder…. (R)eplacement of 6% of 40/60 bitumen by MR6 exhibited slightly reduced post-compaction densification (air voids at refusal density and wheel track rutting), significantly higher stiffness (stiffness modulus) and improved moisture damage resistance.“
| Charlesworth, J. (10 December 2017) “Laboratory Test Report: Bituminous Mixtures – Test Methods for Hot Mix Asphalt BS EN 12697: 2010 Part 44: Crack propagation by semi-circular bending test” 16 Sept 2019 available at https://drive.google.com/file/d/1b9tfr2pQ6NV9qyX3f4ylu5lcTSEkxOSi/view?usp=sharing
Tests were conducted at 0 degrees Celsius and showed improved fracture resistance. Full text can be accessed here.
| Abdullah, M. et al (2017) “Effects of Waste Plastic on the Physical and Rheological Properties of Bitumen.” IOP Conference Series: Materials Science and Engineering. 204. 012016. 10.1088/1757-899X/204/1/012016. 09 Sept 2019 from https://www.researchgate.net/publication/317159929_
Physical_and_Rheological_Properties_of_Bitumen“Bitumen was heated and plastic waste was slowly added. Rheological properties of bitumen were performance by penetration, softening point, viscosity and direct shear rheometer test. The results showed that when content of plastic waste increase, the penetration value, softening point and viscosity of bitumen also increase. Generally, plastic waste improves the performance of bitumen when it was added into bitumen. It can be said that the usage helps to improve the performance of the road pavement which also reduces the rutting effect.“
| White, G. (27 Feb 2019) “EVALUATING RECYCLED WASTE PLASTIC MODIFICATION AND EXTENSION OF BITUMINOUS BINDER FOR ASPHALT” Eighteenth Annual International Conference on Pavement Engineering, Asphalt Technology and Infrastructure, At Liverpool, England, United Kingdom, 27-28 February. 09 Sept 2019 from
and_Extension_of_Bitumous_Binder_for_Asphalt“Three commercially available recycled plastic products for binder extension and modification were evaluated in the same stone mastic asphalt mixture in the laboratory. … No adverse effect was detected with regard to toxic fume generation or hazardous leachate.“
| Utibe, J. et al. “Characterization of Bitumen/Plastic Blends for Flexible Pavement Application” International Conference on Sustainable Materials Processing and Manufacturing, SMPM 2017, 23-25 January 2017, Kruger. Elsevier. 14 Oct 2019 from https://www.sciencedirect.com/science/article/pii/S2351978916302141/.
Waste plastic materials including low density polyethylene (LDPE) grocery bags, etc. are disposed through landfills: this poses an environmental pollution due to difficulty in degradation of polymeric materials by environmental factors. Waste plastic materials can improve desired properties of bituminous mix for repairs and construction of flexible pavements. In this project, various proportions of polymeric materials (5%, 10% and 15%) blended with bituminous mix were characterized. Strength and performance of bitumen/plastic blends were tested through Marshal Stability test, extraction test, sieve analysis, water absorption tests and bulk density. The results showed that the bitumen/plastic blend has higher Marshall Stability of range 14.03 to 14.80 kN compared to the conventional bituminous mix sample which value was 11.35 kN. They also showed higher void air, lower bulk density and Marshall flow than the conventional bituminous mix. The results from the proportions of aggregate and quarry dust (40:60, 50:50 and 60:40) used in the sieve analysis showed ratio 50:50 to be more appropriate for the bitumen/plastic blends. This project also proves that waste plastics can be used efficiently for road repairs and construction resulting in more sustainable and better roads with high performance and durability.