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

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. [ABSTRACT FROM AUTHOR]