Specific Gravity of Fine Aggregate -Pycnometer Procedure [2019]

Specific gravity of fine aggregate procedure by pycnometer is required to find out the aggregate density compared with water. We described the procedure of specific gravity test of fine aggregate as per IS Code with Limits and Calculations by pycnometer.

 

Specific Gravity of Fine Aggregate by Pycnometer Method

What is Specific Gravity of Fine Aggregate?

The specific gravity of an aggregate is density compared with water density. Specific gravity value of an aggregate represents how much dense the aggregate is compared with water.

 

Why Specific Gravity Test of Fine Aggregate Required?

  1. For concrete, asphalt or any mix design where aggregate is used.
  2. By specific gravity, we can guess it’s quality like Bulk density, etc..

 

Specific Gravity test of Aggregate IS Code

IS Code for Aggregate specific gravity is IS 2386 part 3.

 

Apparatus and Tools Required for Specific Gravity Test of Fine Aggregate

  1. Pycnometer

specific gravity of fine aggregate

  1. Weighing balance ( least count 0.5 gram, capacity not less than 3 kg).
  2. Hot air oven to maintain 100 to 110-degree centigrade.
  3. Non-absorbent plate
  4. Filter paper and funnel
  5. Water absorbent cloth

 

Specific Gravity of Fine Aggregate Test Procedure using Pycnometer Method

  1. Before taking the sample for specific gravity test you should mix properly the total aggregate sample.
  1. If you are collecting the sample from any lot or stacking yard then take at least four samples from different places. Mix together and take sample for specific gravity test by quartering it.
  1. A sample weight for specific gravity test shall be near about one kilogram if you are taking aggregate size between 10 mm to 4.75 mm.
  1. A sample weight shall be near about 500 grams if you are taking aggregate finer than 4.75 mm.
  1. After taking the sample, place it in a deep tray or container and fill the water up to a minimum 50 mm above from the top of the aggregate. So take container which has such capacity to submerge the aggregate.
  1. Immediately after submerging aggregates in water take a rod and agitate aggregate to remove air bubbles from the aggregate surface, and leave it for 24 +/- 0.5 hours.
  1. Immediately after 24 hours drain the water by using funnel and filter paper carefully, while draining care shall be taken any aggregate particle retained on filter paper shall be returned to the tray.
  1. Then place the aggregates in pycnometer, fill the distilled water in pycnometer up to the top.
  1. Pycnometer cone shall be properly tight with rubber washer inside. Check washer rubber before use. It shall not be any type of damaged or cut mark.
Important point
  1. No air bubbles shall be inside the pycnometer, if there, then rotate or slightly shake the pycnometer.
  1. Fill distilled water up to apex hole in cone, until the top surface of the water is flat.
  1. Before taking the weight, the outer surface of the pycnometer must be clean with a water-absorbent cloth.
  1. Note down the weight A1 ( pycnometer + water + aggregate )
  1. Shift aggregates and water from pycnometer to clean tray carefully, no particle should remain in pycnometer.
  1. Fill distilled water in pycnometer again up to the top of cone hole like you did before.
  1. Again outer surface of pycnometer must be dried, and take the weight ( weight A2 )
  2. Weight in water a = ( weight A1 – weight A2 )
  1. For specific gravity value, we need weight in water, surface saturated dry weight and oven-dried weight for specific gravity and apparent specific gravity value.
  1. Aggregate shall be spread in a non-absorbent plate and plate shall be placed in air.

Careful while SSD

specific gravity of fine aggregate pycnometer

  1. Avoid aggregates from sunlight or hot air.
  1. Do not use any water-absorbent cloth, it can absorb moisture from aggregate pores. It can change the Aggregate specific gravity value.
  1. While drying turns over the aggregates one by one or use spatula.
  1. Immediately after dry, the surface of aggregates take the weight, It is SSD weight ( surface saturated dry weight ). note down ( weight b )
  1. Place these aggregates in a hot air oven for 25 +/- 0.5 hours.
  1. Maintain the temperature between 100 to 110 degrees centigrade in a hot air oven.
  1. After 24 hours keep out aggregates and allow it to be cool in atmosphere temperature for at least 10 minutes.
  1. Take the weight of oven-dried aggregates. ( weight c ).

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Specific Gravity Formula and Calculation

Specific gravity = c / ( b – a ),

Apparent specific gravity = ( b – c ) / c 

where

c – oven dried weight

b – surface saturated dry weight

a – weight in water

 

Specific Gravity of Fine Aggregate Limit

The limit of specific gravity of Fine aggregate is not fixed but it comes between 2.0 to 3.0 generally.

 

Specific Gravity Units

There are no units for specific gravity because it’s a comparison between aggregate density and water density.

Hope you found good information about specific gravity here.

 

Viva Questions on Specific Gravity of Fine Aggregate

Q.1  What is Specific gravity?

Ans. The specific gravity of any aggregate is its own density compared with water density. Specific gravity value of any aggregate represents how much dense the aggregate is compared with water.

 

Q.2  What is the IS code for Specific gravity of fine aggregate test procedure?

Ans. IS 2386 part 3 is for the specific gravity of aggregates test procedure.

 

Q.3  What is the SSD condition of an aggregate?

Ans. SSD full form is saturated surface dry. for more details about SSD click here

Specific Gravity of Coarse Aggregate -Procedure [2019]

 

Q.4  What is the formula of specific gravity?

Ans. Specific gravity = c / ( b – a ),

Apparent specific gravity = ( b – c ) / c 

where

c – oven-dried weight

b – surface saturated dry weight

a – weight in water

 

Q.5  What is the unit of specific gravity?

Ans. There is no unit of specific gravity.

 

Any other Question? Just ask in comment. We are waiting.

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