Specific Gravity and Absorption of Fine Aggregate: Output
Bulk Specific Gravity @ 23°C:
Bulk Specific Gravity (Saturated Surface-Dry) @ 23°C:
Apparent Specific Gravity @ 23°C:
Bulk specific gravity, apparent specific gravity and absorption of fine aggregate (after 15–19 h of soaking in water) is determined based on AASHTO T 84-13 / ASTM C 128-12 test method.
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 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.
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.
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.
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.
Pycnometer - A volumetric flask of 500-mL capacity, a fruit jar fitted with a pycnometer top or other suitable container into which the fine aggregate test sample can be easily added. The volume of the container filled to mark shall be at least 50 percent greater than the space required to accommodate the test sample.
Mold and Tamper - A metal mold in the form of a frustum of a cone with 40 ± 3 mm inside diameter at the top, 90 ± 3 mm inside diameter at the bottom, and 75 ± 3 mm in height made of metal having a minimum thickness of 0.8 mm. A metal tamper having a mass of 340 ± 15 g and having a flat circular tamping face 25 ± 3 mm in diameter.
Oven of appropriate size capable of maintaining a uniform temperature of 110 ± 5°C (230 ± 9°F).
Obtain the sample for test in accordance with AASHTO T 2.
Prepare approximately 1 kg of the fine aggregate obtained from the sample as per AASHTO T 248 for the test.
Dry the sample in a suitable pan or vessel to constant mass at a temperature of 110 ± 5°C (230 ± 9°F). Once cooled, cover the sample with water and permit to stand for 15 to 19 h. Alternatively, water absorption can be effected by the addition of at least 6 percent moisture to the fine aggregate and allowed to stand for 15 to 19 h.
After the soaking period, excess water is decanted with care avoiding loss of fines. Spread the sample on a flat, nonabsorbent surface. Apply a gently moving current of warm air, and stir frequently to secure homogeneous drying until the test specimen approaches a free-flowing condition. Follow the cone test procedure to determine whether or not surface moisture is present on the constituent fine aggregate particles.
The conical mold is held firmly on a smooth nonabsorbent surface with the
large diameter down. A portion of the partially dried fine aggregate is placed loosely in the mold by
filling until overflow occurs. Heap additional material above the top of the mold by holding
it with the cupped fingers of the hand holding the mold.
25 light drops (free fall under gravity) of the tamper is applied on the fine aggregate with each drop starting about 5 mm (0.2 in.) above the top surface of the fine aggregate.
The mold is lifted vertically after removing loose sand from the base. The fine aggregate will retain the molded shape if surface moisture is still present. If the fine aggregate slumps slightly, it indicates that it has reached a surface-dry condition.
Fill the pycnometer partially with water. 500 ± 10 g of saturated surface-dry fine aggregate prepared as described above is introduced into the pycnometer. The pycnometer is filled with additional water to approximately 90 percent of capacity and the air bubbles in the pycnometer eliminated by manually rolling and agitating or combination of these actions. Adjust the temperature to 23.0 ± 1.7°C (73.4 ± 3°F) by immersing in circulating water. After bringing the water level in the pycnometer to its calibrated capacity, the total mass of the pycnometer, specimen, and water is determined.
After removing the fine aggregate from pycnometer, dry to constant mass at a temperature of 110 ± 5°C (230 ± 9°F), cool in air at room temperature for 1.0 ± 0.5 h and determine the mass.
Determine the mass of the pycnometer filled to its calibration capacity with water at 23.0 ± 1.7°C (73.4 ± 3°F).
A = mass of oven-dry specimen in air, g;
B = mass of pycnometer filled with water, g;
S = mass of saturated surface-dry specimen, g; and
C = mass of pycnometer with specimen and water to calibration mark, g.
|Specific Gravity||Absorption||Mass Percentage|