Specific gravity relative density Sp Gr It is

Specific gravity (relative density) Sp. Gr: It is the ratio of the density of a material to the density of distilled water at a stated temperature. Most natural aggregates have specific gravity between 2. 4 and 2. 9 (without unite). Sp. Gr. is used in certain computations for concrete mix design or control work, such as, absolute volume of aggregate in concrete. It is not a measure of the quality of aggregate.

Absolute specific gravity refers to the volume of the solid material excluding all pores (particles density only). Apparent specific gravity refers to the volume of solid material including the impermeable pores but not capillary pores (normally required in concrete technology). If the aggregate particles are saturated and surface dry, the term bulk or gross specific gravity is used.

Determination of Sp. Gr. of Aggregates (Archimedes Principle) Coarse Aggregate 1 - Aggregate are oven dried at 105± 5°C overnight and the weight is measured as (A) 2 - Aggregate are soaked in water for 24 hours 3 - Aggregate are taken out from water and rolled in a large absorbent cloth, until all visible films of water are removed and then weighed (B) 4 -Aggregate are then weighed in water (C)

Fine Aggregate. 1 -Aggregate are oven dried to constant weight at 105± 5°C. Measure the dry weight as (D) 2 -Soak them in water for 24 hrs 3 -Stir the sample to bring it to SSD condition. Use the Cone Test for Surface Moisture Determination (Weight as A) 4 -Fill the aggregate in SSD condition into a pycnometer (to a calibrated level) and weight it, (water+pyconomete+agg) (B) 5 -Fill the pyconometer with water only (to a calibrated level) and weight it (water+pyconometer) (C)

Example