AASHTO T 85:2021 Standard Method of Test for Specific Gravity and Absorption of Coarse Aggregate

AASHTO T 85:2021 Standard Method of Test for Specific Gravity and Absorption of Coarse Aggregate. TERMINOLOGY Definitions: 3.1.1. absoiption—the increase in the mass of aggregate due to water in the pores of the material, but not including water adhering to the outside surface of the particles, expressed as a percentage of the dry mass. The aggregate is considered “dry” when it has been maintained at a temperature of 110 ± 5°C (230 ± 9°F) for sufficient time to remove all uncombined water by reaching a constant mass. 3.1.2. specific gravity—the ratio of the mass (or weight in air) of a unit volume of a material to the mass of the same volume of gas-free distilled water at stated temperatures. Values are dimensionless. 3.1.2.1. apparent specific gravity—the ratio of the weight in air of a unit volume of the impermeable portion of aggregate at a stated temperature to the weight in air of an equal volume of gas-free distilled water at a stated temperature. 3.1.2.2. hulk specific gravity—the ratio of the weight in air of a unit volume of aggregate (including the permeable and impermeable voids in the particles, but not including the voids between particles) at a stated temperature to the weight in air of an equal volume of gas-free distilled water at a stated temperature. 3.1 .2.3. bulk specific gravity (SSD)—the ratio of the mass in air of a unit volume of aggregate, including the mass of water within the voids filled to the extent achieved by submerging in water for 15—19 h (but not including the voids between particles) at a stated temperature, compared to the weight in air of an equal volume of gas-free distilled water at a stated temperature. SUMMARY OF METHOD A sample of aggregate is immersed in water to essentially fill the pores. Ills then removed from the water, the water dried from the surface of the particles, and weighed. Subsequently the sample is weighed while submerged in water. Finally, the sample is oven-dried and weighed a third time. Using the mass and weight measurements thus obtained and formulas in the method, it is possible to calculate three types of specific gravity and absorption. SIGNIFICANCE AND USE Bulk specific gravity is the characteristic generally used for calculation of the volume occupied by the aggregate in various mixtures containing aggregate, including portland cement concrete. bituminous concrete, and other mixtures that are proportioned or analyzed on...