Estimation of optimum binder content of recycled asphalt incorporating a wax warm additive using response surface method

Abstract

This paper presents a new approach to estimate the optimum binder content (OBC) of recycled asphalts (RAs) incorporating a warm mix additive based on the interaction effects of compaction temperature, RA content and binder content using volumetric and strength characterisation. The experimental design was developed using response surface method (RSM) based on central composite design for various compaction temperatures (130–160 °C), RA contents (30–50%) and binder contents (4.9–6.0%). Laboratory tests were performed and analysed to meet the desired volumetric and strength properties according to the Malaysian specifications for the design of dense asphalt mixtures. Statistical analysis and mathematical models proposed by RSM were used to determine the OBC. The results showed that compaction temperature is the most significant factor in determining the OBC. There are minimum differences in the OBC variation of samples incorporating different dosage of RA. The developed model can be used for quick estimation of OBC for various levels of compaction temperature and RA content.

Keywords:

• Recycled asphalt
• warm mix additive
• response surface method
• optimum binder content
• volumetric properties
• strength behaviour

Acknowledgements

The authors would like to acknowledge the Universiti Sains Malaysia that has funded this research grant through the Research University Individual Grant Scheme (RUI Grant Number 1001/PAWAM/814231) which enables this paper to be written. The authors would also like to acknowledge the technicians of the Highway Engineering Laboratory at the Universiti Sains Malaysia for their kind assistance.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Universiti Sains Malaysia [RUI grant number 1001/PAWAM/814231].