The effect of reclaimed asphalt pavement (RAP) content and source on the return on investment (ROI)

This study evaluated the impact of using different contents and sources of Reclaimed Asphalt Pavement (RAP) on the bottom-up fatigue cracking of asphalt mixtures and the return on investment (ROI). Two RAP sources were used that primarily provided a significant difference in RAP binder Performance Grade (PG): Source A was a PG 76-22 while Source B was a PG 94-10. Bottom-up fatigue cracking was predicted using Level 1 of the AASHTOWare Pavement Mechanistic-Empirical Design (PMED) software. The ROI was then evaluated using FHWA RealCost. To increase the accuracies of the predictions, volumetric properties and blended binder properties were calculated based on the amount of RAP binder that actively blended with the virgin binder. The accuracies were also increased by determining the AASHTOWare PMED fatigue strength coefficients, k(f1), k(f 2), and k(f3), using flexural bending beam fatigue tests rather than using the global defaults provided by this software. In conclusion, the ROI of the six RAP mixtures based on bottom-up fatigue cracking was found to be affected by both RAP content and RAP source, and because of the effect of RAP source, it could not be generalised that using either a higher or lower RAP content will always provide a higher ROI.