Steps towards the detection of reclaimed asphalt pavement in superpave mixtures

For quality control and quality assurance purposes, it would be desirable to quantify the amount of reclaimed asphalt pavement (RAP) already incorporated in a recycled hot mixture. If RAP is incorporated in higher amounts than approved, without a proper design, it can affect the integrity of the mix and can compromise the performance and lifespan of the pavement. Twelve different laboratory prepared asphalt mixtures with variable virgin asphalt binder grade and RAP content were subjected to multiple testing protocols to determine which variables were most significant for rutting, thermal cracking and mechanical response. Statistical analyses demonstrated that the performance of recycled hot mixtures is the result of the combined effect of the RAP content and the binder grade. It was observed that the quantity of RAP could be strongly related to the results of the indirect tensile strength, flow number, and fracture energy.