10. Quantitative extraction of asphalt from HMA (AASHTO T-164): In this test, a solvent
is used to dissolve the asphalt binder out from an HMA sample, and the aggregates are
recovered. The weight of the mix sample before and after the washing out of the asphalt
is used to calculate the asphalt content, and the recovered aggregates can be used for sieve
analysis. A special bowl is used to soak a specified amount of mix (ranging in weight from
0.5 to 4 kg, for an NMAS of 4.75 to 37.5 mm) in a solvent. A filter ring is placed on the base
of the bowl, and the lid is clamped down. A centrifuge is used to spin the sample in the
bowl at a speed of 3600 rpm (slowly increasing the speed to the maximum). The extraction
fluid is run off the bowl, and the process is continued with fresh charges of solvent until
all of the asphalt has been washed away. At the end of this step, the fines adhering to the
filter paper can be scraped out on the remaining aggregate sample. The filter paper and the
sample are then dried at 110°C to constant mass.
11. Resistance of a compacted HMA specimen to moisture-induced damage (AASHTO T283)
as discussed in Chapter 14.