Effect of mixture composition on the mechanical behaviour of cold recycled asphalt mixtures

ABSTRACT

Cold recycled asphalt mixtures (CRAMs) are generally comprised by reclaimed asphalt pavement, virgin aggregates, bitumen stabilising agents (asphalt emulsion or foamed asphalt) and active filler (Portland cement or hydrated lime). Depending on the type and content of each mixture constituent, the CRAM may exhibit different mechanical behaviours. The aim of this study is to evaluate the influence of mixture composition on the mechanical behaviour of CRAMs. The materials used were collected during the construction of an experimental test section and were used as base course mixtures. From triaxial resilient modulus test and dynamic modulus test, it was found that the type and content of bitumen stabilising agent and active filler substantially influence the behaviour of the CRAM. From triaxial resilient modulus tests, it was observed that the mixtures with cement addition behaved similarly to cementitious materials (independent of the confining pressure), while the ones with hydrated lime resembled a granular material (dependent of the stress-state). The dynamic modulus test results indicated that the CRAMs also exhibit viscoelastic properties. Besides, the test provided a clear difference between mixtures stabilised with either asphalt emulsion or foamed asphalt.

KEYWORDS:

• Cold recycling
• stiffness
• experimental test section
• triaxial resilient modulus
• dynamic modulus

Acknowledgements

The authors would also like to acknowledge Copavel Consultoria e Engenharia Ltda. for the availability of the vibratory compactor equipment and foaming machine, and Arteris for the materials and the construction of the experimental test section.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 [grant number 33002010055P-9], by CNPq [grant numbers 309591/2016-3 and 311256/2016-3] and by ANTT [RDT-FD-7].