Eco-friendly paving materials using waste PET and reclaimed asphalt pavement

ABSTRACT

Waste polyethylene terephthalate (PET) and reclaimed asphalt pavement (RAP) represent two categories of waste materials that are currently enduring major recycling efforts around the world. This study proposes a method to incorporate PET-based additives into asphalt mixtures containing RAP. Waste PET was chemically treated using an aminolysis process to synthesise PET-based additives. The effect of the additives on asphalt binder was then characterised through molecular dynamic simulation (MDS) which indicated that the additives increase the intermolecular interaction within the asphalt binder molecules. Subsequently, binders modified with PET additives were used to prepare mixtures containing RAP at various percentages and tested through conventional rheological tests, such as Marshall Stability tests and Indirect Tensile Stiffness Modulus (ITSM) tests. Mixtures with 2% of PET additives and RAP showed improved stability and Marshall quotient values, demonstrating better resistance to permanent deformation. It was also observed that the PET additives have the substantial effect to reduce the ageing effect of mixtures containing RAP, thereby improving the longevity and service life of pavement mixtures. Overall, the results indicated that the usage of such PET derived additives can have a significant positive effect in improving the performance of asphalt mixtures containing RAP.

KEYWORDS:

• PET
• RAP
• chemical recycling
• sustainability
• paving materials

Additional information

Funding

The authors would like to thank the Hong Kong Research Grants Council, University Grants Committee (Project Number: 15214615) and the Environment and Conservation Fund of the HKSAR Government (Project Number: 84/2017) for providing the financial support of the study presented in this paper.

Notes on contributors

Anand Sreeram

Mr Anand Sreeram is a Ph.D. candidate at the Department of Civil and Environmental Engineering at The Hong Kong Polytechnic University, conducting research on the development of sustainable pavement materials. He received his undergraduate degree in Chemical Engineering and postgraduate degree in Environmental Engineering from The Hong Kong University of Science and Technology. He previously worked as a Research Assistant at the Spanish National Research Council, Spain, focusing on the chemical characterisation of carbonaceous materials. He was awarded the first runner-up in the 2017 Environmental Paper Award of the Environmental Division of The Hong Kong Institution of Engineers.

Zhen Leng

Dr Zhen Leng is an Associate Professor of Civil and Environmental Engineering at The Hong Kong Polytechnic University, where he also serves as the Director of the Hong Kong Road Research Laboratory. He received his Ph.D. degree in Civil Engineering from University of Illinois at Urbana-Champaign in 2011. His research interests mainly include sustainable infrastructure materials and technologies, eco-efficiency analysis and life cycle assessment, and non-destructive evaluation of transportation infrastructure. He is currently a Director of the American Society of Civil Engineers (ASCE) Hong Kong Section, and an Executive Board Member of the Hong Kong Society for Transportation Studies (HKSTS). He also serves as an Associate Editor of Journal of Cleaner Production and ASCE Journal of Transportation Engineering, Part B: Pavements, and an Editorial Board Member of Road Materials and Pavement Design, Transportation Research Part D: Transport and Environment, and International Journal of Pavement Research and Technology.

Rabindra Kumar Padhan

Dr Rabindra Kumar Padhan is a Postdoctoral Researcher at the Department of Civil and Environmental Engineering at The Hong Kong Polytechnic University. He received his Ph.D. degree in Chemistry from the University of Petroleum and Energy Studies, India in 2015. He was previously a research scholar at the Indian Institute of Technology (IIT), Delhi. His research interests include bitumen chemistry, polymer synthesis and waste recycling. He is a holder of 14 national and international patents and has authored eight SCI publications. He was awarded the Indian Oil Golden Jubilee Millennium Fellowship in 2011.

Xin Qu

Mr Xin Qu is a Ph.D. candidate at the Institute of Highway Engineering, RWTH Aachen University in Germany. He received the B.S. degree and the M.S. degree in Highway Engineering from Chang’an University, People's Republic of China. His research interests include the fatigue behaviour, mechanical properties and ageing of asphalt binders from a macro perspective, the chemistry and molecular structure of bitumen fraction at a micro scale as well as biomaterial modified asphalt. He was awarded the National Scholarship of the China Scholarship Council in 2014.