SPECIFIC GRAVITY OF FINE AGGREGATE TEST { IS 2386 Part-3 (1963) }

OBJECTIVE :

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

 APPARATUS: 

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

THEORY:

Specific gravity of fine aggregate (sand) is defined as the ratio of the weight of a given volume of aggregates to the weight of equal volume of water. The specific gravity of fine aggregate (sand) is considered to be around 2.65 to 2.67.

Sand particles composed of quartz have a specific gravity between 2.65 to 2.67. While inorganic clays generally range from 2.70 to 2.80. Soils with large amounts of organic matter or porous particles (such as diatomaceous earth) have specific gravity below 2.60 (Some range as low as 2.00).

The specific gravity of an aggregate is considered as the measure of strength or quality of the material. Specific gravity is defined as the ratio of weight of a given volume of aggregate to the weight of equal volume of water. Aggregates having low specific gravity are generally weaker than those with aggregates having high specific gravity. This property helps in a general identification of aggregates.

PROCEDURE: 

1. Sample of about 500 g shall be placed in the tray and covered with distilled water at a temperature of 22 to 32°C.. The sample shall remain immersed for 24 ± l/2 hours.

2. The water shall then be carefully drained from the sample. 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, The Pycnometer shall be refilled with distilled water to the same level as 21 before, dried on the outside and weighed (weight C).

 5. The water shall then be carefully drained from 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 It shall be cooled in the air-tight container and weighed (weight D).

CALCULATIONS : Specific gravity, apparent specific gravity and water &absorption shall be calculated as follows: 

  Specific gravity =.................... 

Apparent Specific gravity...............

 water absorption............

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.

 

RESULTS :

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

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