This project will develop a new procedure to quantify reclaimed asphalt pavement (RAP) recycled binder availability (RBA) using comparative sieve analysis of RAP and recovered RAP aggregate. Work in Stage 1 will involve ruggedness evaluation to identify how closely the sieve analysis procedural operating factors need to be controlled. A fine RAP sample from Virginia and a comparatively coarse RAP sample from Indiana will be acquired to cover variations in climate, geologic origin, and particle size distribution. Ruggedness testing will be conducted according to ASTM E1169 and ASTM C1067. The experimental factors to be evaluated will include: (1) sample size, (2) washing time, (3) drying temperature, (4) particle separation method, (5) sieving time, (6) asphalt removal method, and (7) unwashed vs. washed sample for aggregate recovery. Statistical analysis will be performed to identify experimental factors with statistically significant effects on RBA. Subsequently, controls for these factors will be established to minimize the impacts of their deviation on the average and variance of RBA results. Stage 2 work will involve an interlaboratory study (ILS) according to ASTM E691 to establish the precision of the RBA results. The study will include a minimum of six participating laboratories from academia, industry, and highway agencies.  Three RAP materials, procured from North Carolina, Virginia, and Indiana with distinct RBA values, will be used. A  protocol outlining the necessary procedures and data reporting for the ILS experiments will be developed for the ILS participants. A webinar will also be organized to educate the ILS participants on the experimental procedure and the ILS protocol. Each lab will execute the required sieve analysis experiments according to the ILS protocol. Statistical analysis of the results will be conducted to define the repeatability (single-operator precision) and reproducibility (multi-laboratory precision) of the RBA results. The research team will work with the ILS participants to develop pilot implementation plans. The final report will include all relevant data, methods, models, and conclusions along with guidance on how to use the sieve analysis procedure in a state DOT.