Influence of reclaimed asphalt pavement (RAP) aggregate fraction on the determination of active binder content

Gradation plays significantly towards the amount of active binder in hot mix recycling, as a function of exposed specific surface of aggregates. Existing procedures do not explicitly consider gradation of the Reclaimed Asphalt Pavement (RAP) mixture in the determination of active binder content (RAb). In this investigation, two types of RAP reclaimed after six and eight years of service life are used to quantify RAb. The RAP material is sieved into three different sizes representing coarse, fine, and filler fraction and the corresponding binder content is determined. Gradation of extracted aggregate obtained from centrifuge and ignition oven is determined. The RAb mobilized is quantified based on a mechanical mixing procedure with the virgin aggregate of a threshold sieve size. The variation in RAb in the different size fractions is identified, and the need of varied mixing time and rejuvenator dosage for beneficial binder mobilization among the different fractions is also identified.