Applicability of Cohesion Test in the Estimation of Effective RAP Binder

Due to the increased utilization of Recycled Asphalt Pavement (RAP) in pavement construction, the need for RAP characterization using a robust and simple laboratory protocol has become inevitable. This has led to a Round Robin Test organized by the RILEM Technical Committee 237-SIB with the aim of developing a new protocol for providing quality control for the design of RAP mixes. Generally, for the design of hot-mix asphalt with RAP, 10–50% of RAP material is being used by different agencies. Though the degree of RAP binder availability can vary anywhere between 0 &100%, most agencies assume 100% RAP binder availability for HMA design. The cohesion test has been recommended by the RILEM committee as an indicative test to quantify the degree of activity (DoA) of the RAP binder. The current study adopted the RILEM protocol and investigated seven different RAP sources including artificially aged RAP. The cohesion test was performed at three conditioning temperatures of 100, 120 and 140 °C. The test results indicate that the cohesion test gives a clear indication of the level of binder activity in the RAP. For the different sources, the DoA was observed to vary between 12–100%. The maximum DoA is obtained at 140 °C, ranging from 25 to 100%.