LABORATORY EVALUATION ON THE INCOMPATIBILITY OF WASTE POLYMER MODIFIED BITUMEN

Abstract

The pollution of waste polymers such as Rubber and plastic has become the most challenging environmental issues due to the dramatic increase in the generation of polymers products. The polymer market, which was valued at USD 629.4 billion in 2021, is projected to rise at a compound annual growth rate of 4.69% from 2023 to 2030, reaching a total estimated value of USD 1046.15 billion. It is known that Pakistan generates 1000–2000 tons of waste polymers annually. Accordingly, due to environmental challenges, engineers and researchers sought to use polymers waste in engineering projects as a contribution to preserving the environment. Modifying bitumen with polymers waste is one of the common approaches to reduce the amount of global polymers waste. It is documented that mixing bitumen with Crumb rubber significantly enhances the physical and rheological properties of bitumen. However, one of the main challenges facing researchers regarding modification of bitumen with crumb waste is incompatibility. The occurrence of incompatibility is attributed to the difference in the density and polarity between crumb rubber and bitumen. In addition, incompatibility negatively affects the performance of the asphalt layer, which, in turn, significantly decreases the lifespan of the asphalt layer. Furthermore, modifying bitumen with crumb rubber poses a significant challenge for asphalt mixing plants due to the high viscosity of crumb rubber-modified bitumen, which requires an increase in mixing energy to achieve homogeneity. The increase in the energy of mixing may increase the cost of production, which is considered a challenge in modifying bitumen with crumb rubber. Therefore, this project is aimed to introduce novel contributions in terms of eliminating the drawbacks of modifying bitumen with waste polymers such as crumb rubber in terms of incompatibility and high viscosity of Rubberized-amended bitumen. However, in this project, the polymerized-modified bitumen will further be amended with the additive of titanium dioxide to improve the incompatibility and decrease the viscosity of crumb rubber modified bitumen.