Asphalt-rubber gap-graded mixture design practices: a state-of-the-art research review and future perspective

Abstract

The use of asphalt-rubber gap-graded (AR-Gap) mix as a pavement material has gained importance due to its environmental benefits and enhanced performance. This paper reviews the current state-of-the-art pertinent to AR-Gap mix design research and practice. The various mix design practices of AR-Gap mixes adopted by various agencies were summarised. Furthermore, the performance characteristics of AR-Gap mixes such as drain-down, moisture susceptibility, permanent deformation, and fatigue cracking were also documented. The field performances of AR-Gap pavements were also reviewed. Due to an increased use of AR-Gap as a pavement material owing to its several benefits, there exists an extensive scope for further research to understand the material better, which will make it a promising sustainable pavement material in future. Furthermore, considering that AR-Gap mix design and construction technologies are yet to be fully implemented worldwide, the present work aims to be an up-to-date reference to provide benefits and issues associated with the AR-Gap mixes. However, based on the various research questions emanating out of the review process, it was adjudged that there is still further scope for advancing the current state-of-the-art pertaining to the AR-Gap mix design, and the contribution of rubber inclusions in assisting the mix’s augmented performance.

Keywords:

• asphalt rubber
• gap-graded gradation
• crumb-rubber
• mix design
• performance evaluation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Government of India Department of Science and Technology [grant number: SERB/F/2670/2014-15, dated 17 July 2014].