Early-age performance characterization of hot-mix asphalt overlay with varying amounts of asphalt binder replacement

Abstract This study examined five field projects in Illinois, with eight different surface mixes having varying asphalt binder replacement (ABR) achieved by using binders from recycled asphalt shingles (RAS) and reclaimed asphalt pavement (RAP). The performance testing was conducted on plant-mixed laboratory-compacted (PMLC) specimens and consisted of dynamic modulus, overlay tester, Illinois Flexibility Index Test (I-FIT), flow number, and Hamburg wheel tracking tests. The early-age field performance was evaluated, and correlation with performance tests was conducted. Results showed that ABR, asphalt content, and binder grade have effects on rutting and cracking resistance. No rutting issues were found with any of the tested mixes. The flexibility index (FI) values of field cores were higher than PMLC specimens, as no specimen thickness and air void corrections were applied at this time. I-FIT is recommended as a simple performance test to screen and distinguish between mixes for potential cracking.