Bulk Dry Specific Gravity The volume measurement includes the overall volume of

Bulk dry specific gravity the volume measurement

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Bulk Dry Specific Gravity: The volume measurement includes the overall volume of the aggregate particle as well as the volume of the water permeable voids. The mass measurement only includes the aggregate particle. Bulk Saturated Surface Dry (SSD) Specific Gravity: Volume measurement includes the overall volume of the aggregate particle as well as the volume of the water permeable voids. The mass measurement includes the aggregate particle as well as the water within the water permeable voids. Procedure: 1. Obtain a sample of coarse aggregate material. This sample size is based on nominal maximum aggregate size (NMAS). Sample sizes range from 2 kg for a 12.5 mm NMAS to 5 kg for a 37.5 mm NMAS. 2. Wash the aggregate retained on the No. 4 (4.75 mm) sieve. Dry the material until it maintains a constant mass. This indicates that all the water has left the sample. Drying should occur in an oven regulated at 110°C. Cool the aggregate to a comfortable handling temperature. Immerse the aggregate in water at room temperature for a period of 15 to 19 hours.
3. Dry the sample to a saturated surface dry (SSD) condition. Rolling up the aggregate into the towel and then shaking and rolling the aggregate from side to side is usually effective in reducing the sample to SSD condition. Once there are no visible signs of water film on the aggregate particle surfaces, determine the sample mass (B). 4. Place the entire sample in a basket and weigh it underwater (C). 5. Remove the aggregate from the water and dry it until it maintains a constant mass. Drying should occur in an oven regulated at 110°C for 24 hours then determine the mass (A). Three different masses are recorded during the test. Their common symbols are: A = mass of oven-dry sample in air (g) B = mass of SSD sample in air (g) C = mass of SSD sample in water (g) Mass of oven-dry sample in air (g), A Mass of SSD sample in air (g), B Mass of SSD sample in water (g), C

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