Performance of Plastic Waste and Waste Engine Oil as Partial Replacement of Bituminous Asphalt Concrete in Flexible Pavements

Abstract

Plastic waste is an emerging issue posing serious pollution problems to the environment. Waste Engine Oil has also become an environmental nuisance causing water pollution and soil degradation. In addition to the emerging environmental issues, the sources of bitumen for road construction are continuously being depleted hence the need for innovative ways of sustaining road construction through use of plastic waste and waste engine oil. This research project reviewed available literature on the concept of using HDPE waste plastic and waste engine oil as partial replacements of bitumen in road construction together while also carrying out the Marshall Stability test in both neat and bituminous mixes modified with plastic waste and waste engine oil. The optimum bitumen content was determined as 6% from the neat samples. Samples of the modified mix were then prepared with the percentage plastic content varying as 10%, 20%, 30%, and 40% of the mass of bitumen. The optimum plastic content was determined at 18% with a stability value of 8580N (an increase from 8337.4N for the neat samples). Samples with both plastic waste and waste engine oil replacements were prepared with 18% plastic waste being replaced with 10%, 20%, 30%, and 40% waste engine oil while bitumen content remained constant at 6%. The optimum replacement was determined at 19% giving the highest stability of 8820N (an increase of 2.8% from the plastic only modified mix and an increase of 5.8% from the neat sample). The use of polymer modified bituminous mix in the construction of flexible pavements, the problems of pollution and improper waste disposal would be mitigated. Implementation of such innovative technology in highway construction not only improves the environment but also increases its road life. Results from the Marshall Stability test showed that an optimum plastic content of 18% gave the highest stability. Both the values of stability (8820N) and flow (2.9mm) fell within the AASHTO specified recommendations of 7000N minimum for stability and 2-4mm for flow. Volumetric properties of bulk density, voids in mineral aggregates, voids in mix and voids filled with bitumen also fell within acceptable ranges