Application and validation of the cohesion test to characterise reclaimed asphalt pavement

Abstract

Cold recycled bituminous materials can consist of up to 100% reclaimed asphalt pavement (RAP) treated with different binders such as bituminous emulsion and foamed bitumen, as for Hot recycling the highest percentage is trying to be achieved, recent studies suggest 40% as a possible percentage of RAP in hot asphalt mixtures, actually some countries have this percentage in their specifications and others even more (i.e. Japan). These high percentages of RAP make it necessary to completely characterise the material before proceeding with the mix design, as it is done for all the other components of bituminous mixtures. There is only one protocol to characterise the RAP, recently published on Materials and Structures as a RILEM Recommendation: Recommendation of RILEM TC237-SIB: Protocol for characterisation of recycled asphalt (RA) materials for pavement applications. This paper aims to verify the capability of cohesion test developed in RILEM TC 237-SIB to differentiate RAP properties. To do this, cohesion tests were performed on four different RAP sources in two universities. The RAPs were forcibly aged with two different methods which are boiling + ultra-violet, and oven aged. The ITS values of RAP before and after ageing are significantly different, and the ITS change caused by the ageing differs for the two used lab ageing methods. The results obtained in the described experimental campaigns show that the cohesion test is able to clearly differentiate RAPs and that cohesion test can be efficiently used to classify RAPs.