AASHTO T 166:2021 Standard Method of Test for Bulk Specific Gravity ( Gmb) of Compacted Asphalt Mixtures Using Saturated Surface-Dry Specimens.
Weighing Device—The weighing device shall have sufficient capacity, be readable to 0.1 percent of the specimen mass or better, and conform to the requirements of M 231. The weighing device shall be equipped with a suitable suspension apparatus and holder to permit weighing the specimen while suspended from the center of the scale pan of the weighing device.
5.2. Suspension Apparatus—The wire suspending the container shall be the smallest practical size to minimize any possible effects of a variable immersed length. The suspension apparatus shall be constructed to enable the container to he immersed to a depth sufficient to cover it and the test specimen during weighing. Care should be exercised to ensure no trapped air bubbles exist under the specimen.
5.3. Waler Bath—For immersing the specimen in water while suspended under the weighing device. equipped with an overflow outlet for maintaining a constant water level.
Dry the specimen to a constant mass at a temperature of 52 ± 3°C (125 ± 5°F). Specimens saturated with water shall initially be dried overnight and then weighed at 2-h drying intervals. Recently compacted laboratory specimens. which have not been exposed to moisture, do not require drying. As an alternative to oven drying to constant mass, drying the specimen according to R 79 may be used. When using R 79 to achieve constant mass, perform the drying procedure at least twice, with a mass determination after each drying cycle.
6.2. Cool the specimen to room temperature at 25 ± 5°C (77 ± 9°F), and record the dry mass as A (Note 2). Immerse each specimen in the water bath at 25 ± 1°C (77 ± 1.8°F) for 4 ± 1 mill, and record the immersed mass as C. Remove the specimen from the water bath; damp-dry the specimen by blotting it with a damp towel, and determine the surface-dry mass as B as quickly as possible (11w entire operu(ioiz is not to exceed 15 s). Any water that seeps from the specimen during the weighing operation is considered part of’ the saturated specimen. Each specimen shall be immersed and weighed individually.
Note 2 —If desired, the sequence of testing operations may be changed to expedite the test results. For example, first the immersed mass C can be taken, then the surface-dry mass B, and finally the dry mass A.
Note 3—Terry cloth has been found to work well for an absorbent cloth. Damp is considered to be when no water can be wrung from the towel.AASHTO T 166 pdf download.