Water Absorption Test Procedure of Coarse and Fine aggregate is required to find out the water absorption capacity of aggregate in its tiny pores. We described water absorption test procedure of aggregate as per IS Code.
What is Water Absorption of Aggregate?
Water Absorption Test Definition
Water absorption of an aggregate is a weight percentage of the same aggregate in which water can be absorbed.
Why Water Absorption of Aggregate Required?
Each and every size of aggregate has so many pores inside it. These are very tiny pore holes. We cannot see it with our nude eyes. More tiny pore holes make the aggregates more weak in strength. So that the Indian standard has fixed a limit of water absorption for use in any type of construction work.
Water Absorption Test of Aggregate IS Code
IS Code 2386 part 3.
Apparatus and Tools required for Aggregate Water Absorption test
- Weighing balance with least count 0.5 gram, capacity minimum 3000 gram.
- Deep tray or container or bucket having a minimum 5-liter capacity to store water.
- Hot air oven to maintain 100 to 110 degree centigrade temperature.
- Non-absorbent plate, glass or metal.
Precautions Before Water absorption Test of Aggregate
Water absorbent cloth should not be used because it absorbs water from aggregate pores.
If it absorbs water from pores then SSD weight ( surface saturated dry weight ) can be decreased and we can not get the accurate result.
Surface saturated dry condition of an aggregate is when it’s all tiny pores full of water but the surface of aggregate is dry. It gives cool feeling when you touch aggregate.
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Procedure of Aggregate Water Absorption test
This procedure is useful for 10 mm to 40 mm size of aggregates.
- Take aggregate near about 2 kilograms, but not less than 2 kilograms by mixing the total sample of aggregate.
- If you are taking the aggregate sample from any lot then sampling shall be done from not less than four places.
- Then wash the aggregate sample to remove the fine materials stuck on the surface of the aggregates.
- Allow it to drain water for at least five minutes.
- Then put this sample in a container in which water storage capacity is not less than 5 liters.
- Pour the water in the container until its fulled minimum 50 mm above from the top of the aggregates.
- Agitate with any clean rod to ensure no air bubbles stuck on the surface of the aggregates.
- Leave it for 24 +/- 0.5 hours.
- After 24 hours, Keep out the aggregates from water and keep on a glass plate, metal plate or any type of non- absorbent plate.
- Place this plate with aggregates in air.
- Do not place the sample in sunlight or hot air.
- Do not use any absorbent cloth, it can absorb moisture from aggregate pores.
- Spread aggregates in a plate to make it surface saturated dry.
- Turn over the aggregates time to time while drying.
Careful with SSD
- When it looks like that no moisture available on the aggregate surface but inside pores, then take weight without any delay.
- That is called surface saturated dry weight ( SSD weight ) of aggregate.
- For water absorption of aggregate, you need two values, the first value is surface saturated dry weight of aggregate and the second value is oven-dried weight.
- After SSD weight, place the aggregates in the oven, set the temperature between 100 to 110-degree centigrade.
- Leave it to dry for 24 +/- 0.5 hours.
- After 24 hours, keep it out and allow it to be cool in the atmosphere temperature for at least 10 minutes.
- Write down the oven-dried weight of aggregate.
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Water Absorption Test Formula, Calculation and Report
or water absorption test for concrete formula
water absorption (%)= [(SSD wt – Dry wt) / Dry wt] * 100
Aggregate Water Absorption Limit
The water absorption limit of coarse or fine aggregate
For Concrete – 2%
For Bituminous concrete – 2%
For any Asphalt Concrete – 2%
Viva Questions on Water Absorption Test
Q.1 What is water absorption?
Ans. Water absorption of an aggregate is the percentage of water weight which absorbed into aggregate tiny pores during 24 hours soaking in water.
Q.2 What is the IS code for water absorption test of coarse or fine aggregate?
Ans. The IS code used for water absorption test of coarse or fine aggregate is IS 2386 part 3.
Q.3 What is the meaning of SSD condition of an aggregate? ( I faced this in two interviews)
Ans. The full form of SSD is a Saturated Surface Dry condition.
When an aggregate soaked in water for 24 hours, then kept out for dry (not in sunlight) in shade.
After some time, surface moisture of aggregate will be dry only but not inside pores of aggregates.
That condition is called Saturated surface dry condition. If you touch the aggregate, you feel cool.
Q.4 What is the water absorption limit for concrete?
Ans. The water absorption limit for concrete is 2%.
Any other Question? Just ask in Comment. We are waiting.
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