ASTM C127:15 pdf free download – Standard Test Method for Relative Density (Specific Gravity) and Absorption of Coarse Aggregate.
Note 2—When testing coarse aggregate of large nominal maximum size requiring large test samples, it may be more convenient to perform the test on two or more subsamples, and the values obtained combined for the computations described in Section 9.
8. Procedure
8.1 Dry the test sample in the oven to constant mass at a temperature of 110 ± 5 °C, cool in air at room temperature for I to 3 h for test samples of 37.5-mm (1 ½-in.) nominal maximum size, or longer for larger sizes until the aggregate has cooled to a temperature that is comfortable to handle (approximately 50 °C). Subsequently immerse the aggregate in water at room temperature for a period of 24 ± 4 h. When Specification C330 or Specification C332 Group II lightweight aggregates are used, immerse the aggregate in water at room temperature for a period of 72 ± 4 h. stirring for at least one minute every 24h.
8.2 When the absorption and relative density (specific gravity) values are to be used in proportioning concrete mixtures in which the aggregates will be in their naturally moist condition, the requirement in 8. 1 for initial drying is optional, and, if the surfaces of the particles in the sample have been kept continuously wet until tested, the requirement in 8.1 for 24 ± 4 h or 72 ± 4 h soaking is also optional.
Noi 3—Values for absorption and relative density (specific gravity) (SSD) may be significantly higher for aggregate not oven dried before soaking than for the same aggregate treated in accordance with 8. 1. This is especially true of particles larger than 75 mm since the water may not be able to penetrate the pores to the center of the particle in the prescribed soaking period.
8.3 Remove the test sample from the water and roll it in a large absorbent cloth until all visible films of water are removed. Wipe the larger particles individually. A moving stream of air is permitted to assist in the drying operation. Take care to avoid evaporation of water from aggregate pores during the surface-drying operation. Determine the mass of the test sample in the saturated surface-dry condition. Record this and all subsequent masses to the nearest 0.5 g or 0.05 % of the sample mass, whichever is greater.
8.4 After determining the mass in air, immediately place the saturated-surface-dry test sample in the sample container and determine its apparent mass in water at 23 ± 2.0 °C. Take care to remove all entrapped air before determining its mass by shaking the container while immersed.
Nom 4—The difference between the mass in air and the mass when the sample is submerged in water equals the mass of water displaced by the sainple.
NOTE 5—The container should be immersed to a depth suflicient to cover it and the test sample while determining the apparent mass in water.
Wire suspending the container should be of the smallest practical size to minimize any possible effects of a variable immersed length.