Cracking potential evaluation of recycled asphalt materials using the poker chip test and I-FIT

High amounts of recycled material in asphalt concrete (AC) pavements often increase the risk of cracking. Although the use of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) reduces the need for virgin asphalt binders and aggregates, substituting stiff recycled materials can cause embrittlement of the binder blend and consequently the mix. This study focuses on evaluating the resistance to cracking of recycled asphalt materials through laboratory tests conducted at binder and mixture levels. Initially, seven virgin asphalt binders were tested using the poker chip test at three ageing levels. Next, 21 dense-graded AC mixtures were prepared using the same set of binders and tested at short- and long-term ageing levels using the Illinois Flexibility Index Test (I-FIT). Finally, asphalt binders were extracted from the AC mixtures and subjected to the poker chip test to assess the cracking resistance of binders containing recycled materials to establish a potential relationship among the results for the binders and the AC mixtures. The results demonstrate the poker chip test's ability to differentiate binders based on modification and ageing. Both I-FIT and poker chip tests effectively identified stiff AC mixtures containing high amounts of recycled materials. However, the poker chip test was more sensitive to binder modification or PG. Additionally, a comparison was made between the frequency sweep test, which operates within the linear viscoelastic (LVE) range of an asphalt binder, and the poker chip test. It was concluded that a test conducted within the LVE range of asphalt binders was insufficient to compare the behaviour of recovered asphalt binders, whereas the poker chip test effectively demonstrated this ability, aligning well with results from I-FIT.