Synergic effect of waste PET and sebacic acid on the rheology of crumb rubber modified bitumen

ABSTRACT

Existing research has shown that the inclusion of polyethylene terephthalate (PET)-based additives can help in improving the performance of crumb rubber-modified bitumen (CRMB). However, its field applicability is limited as a result of inadequate storage stability and phase separation issues. This study was concerned with the further improvement in the stability of such binders by the incorporation of a dicarboxylic acid group into the blend, achieved with the addition of sebacic acid. The CRMB binders were prepared by the additives synthesised from waste PET and sebacic acid at different proportions, and tested through various conventional binder tests, storage stability test, superpave performance grading, Marshall Stability tests and Hamburg wheel tracking tests. The results indicated that the combination of sebacic acid and PET additives considerably improved the storage stability of CRMB, to within the acceptable limits for field applicability. It was further proposed that the chemical interaction of these additives with bitumen will help in increasing the phase integrity of CR in the bitumen matrix. From the various rheological tests conducted, it was also seen that the modified binders provided comparative performance at high temperatures when compared to CRMB, and improved performance at intermediate and low temperatures.

KEYWORDS:

• Bitumen
• crumb rubber
• PET additive
• sebacic acid
• storage stability

Acknowledgments

The work conducted in this paper was funded by Indian Oil Corporation Limited, R & D Centre Faridabad, India. The authors wish to acknowledge Dr. Amol D., Mr. R.S. Negi, Mr. Dhanesh Kumar, Mr. David K., Dr. I. Devotta of the bitumen department, Indian Oil R&D Centre for their valuable support and fruitful discussion. Dr. Chandra Sekhar Mohanta is also grateful to Indian Oil R&D for providing ‘Indian Oil Golden Jubilee Research Fellowship’ and infrastructure support for this research.

Disclosure statement

No potential conflict of interest was reported by the authors.