Determination of Specific Gravity of Fine Aggregate

Objective : To determine specific gravity of a given sample of fine aggregate.


Reference :  IS : 2386 ( Part III ) - 1963

Apparatus : Pycnometer, A 1 000-ml measuring cylinder, well-ventilated oven, Taping rod, Filter papers and funnel, etc.

Figure :

Procedure :

1. A sample of about 500 g shall be placed in the tray and covered with distilled water at a temperature of 22 to 32°C. Soon after immersion, air entrapped in or bubbles on the surface of the aggregate shall be removed by gentle agitation with a rod. The sample shall remain immersed for 24 ± l/2 hours.

2. The water shall then be carefully drained from the sample, by decantation through a filter paper, any material retained being return& to the sample. The fine aggregate including any solid matter retained on the filter paper shall be exposed to a gentle current of warm air to evaporate surface moisture and the material just attains a ‗free-running‘ condition. The saturated and surface-dry sample shall be weighed (weight A).

3. The aggregate shall then be placed in the pycnometer which shall be filled with distilled water. Any trapped air shall be eliminated by rotating the pycnometer on its side, the hole in the apex of the cone being covered with a finger. The pycnometer shall be dried on the outside and weighed (weight B).

4. The contents of the pycnometer shall be emptied into the tray, care being taken to ensure that all the aggregate is transferred. The pycnometer shall be refilled with distilled water to the same level as

before, dried on the outside and weighed (weight C).

5. The water shall then be carefully drained from the sample by decantation through a filter paper and

any material retained returned to the sample. The sample shall be placed in the oven in the tray at a

temperature of 100 to 110°C for 24 f l/2 hours, during which period it shall be stirred occasionally to

facilitate drying. It shall be cooled in the air-tight container and weighed (weight D).

6. Calculations— Specific gravity, apparent specific gravity and water &sorption shall be calculated as follows:

A = weight in g of saturated surface - dry sample,

B = weight in g of pycnometer or gas jar containing sample and filled with distilled water,

C = weight in g of pycnometer or gas jar filled with distilled water only, and

D = weight in g of oven - dried sample.

Conclusion / Result : 

i) The Specific Gravity of a given sample of fine aggregate is found to be …….

ii) The Water Absorption of a given sample of fine aggregate is found to be ……. %