AASHTO T166:16(2020) Standard Method of Test for Bulk Specific Gravity (Gmb) of Compacted Asphalt Mixtures Using Saturated Surface-Dry Specimens.
5.1. Weighing Device—The weighing device shall have sufficient capacity, he readable to 0.1 percent of the sample mass or better, aiid conform to the requirements of M 23 I. 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 he the smallest practical size to minimize any possible effects of a variable immersed length. The suspension apparatus shall he constructed to enable the container to he immersed to a depth sufficient to cover it and the test sample during weighing. Care should he exercised to ensure no trapped air bubbles exist tinder the specimen.
5.3. Water Bath—For immersing the specimen in water while suspended under the weighing device, equipped with an overflow outlet for maintaining a constant water level.
6.1. Dry the specimen to a constant mass at a temperature of 52 ± 3°C (125 ± 5°F). Samples saturated with water shall initially be dried overnight and then weighed at 2-h drying intervals. Recently compacted laboratory samples, which have not been exposed to moisture, do not require drying. As an alternative to oven drying to constant mass, drying the sample 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 mm, 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 (the entire operation 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 he changed to expedite the test results. For example, first the immersed mass C can he 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 he when no water can he wrung from the towel.
7.1. Calculate the bulk specific gravity (G,h) of the specimen as follows.AASHTO T166 pdf download.