In this article, I have explained 15 important points to be remembered For Civil Engineer regarding Fine Aggregate. It comprises of the size of coarse Grained soil, Fine grain soil, specific Gravity, Impurities available in sand, Field Test, Sieves, Test of sand, and Characteristics of good quality of Fine Aggregates.
Following are the 15 Important points about Fine Aggregates.
1. Different sizes of Coarse Grained soil
- Boulders Greater than 300 mm.
- Cobble 80 mm – 300 mm.
- Gravel 4.75 mm – 80 mm.
- Sand 75 micron – 4.75 micron.
2. Size of Fine Grained soil
- Silt 2 micron – 75 micron.
- Clay less than 2 micron.
3. Specific Gravity
- Specific gravity of Fine Aggregate is ranges from 2.55 to 2.65.
4. Impurities available in Fine Aggregates
- Organic matter.
5. Sieve used for grading of Coarse Aggregates
80 mm, 63 mm, 40 mm, 20 mm, 16 mm, 12.5 mm 10 mm, 4.75 mm, 2.36 mm.
6. IS Sieve used for grading of Fine Aggregates
10 mm, 4.75 mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron, 150 micron.
7. Fine Modulus of Fine Aggregates
Type of sand fineness Modulus Range
Fine sand 2.2-2.6
Coarse Sand 2.9- 3.2
8. Field Test of Fine aggregate
- Fine Aggregate will not stick with hand. If it contains clay will stick and if the color of the palm changes that indicate fine aggregate has clay and silt.
- If you add a small quantity of sand in a glass of water if it settles immediately which means it is suitable for construction work if the sand form different layer at the top that indicates that sand has a layer of silt at the top. The thickness of the silt layer should not be more than the thickness of the layer by 8%.
- If we add caustic soda in a glass of water and later add sand inside the glass, if water changes the color to brown then it shows that it has some organic impurities which are not suitable for construction work.
- It should be free from lumps, vegetable matter, organic impurities, etc.
9. Test of Fine Aggregate
- Bulking of sand.
- Silt content
- Fineness modulus
- Sieve analysis
10. Bulking of Sand
It is obtained from the following formula
% Bulkling of sand= (H1-H2/H2) x 100.
Where H1= Height of sand in one container
H1= height of water in another container. Add the sand in water and measure the height of sand in water is H2.
11. Silt Content Test(IS 2386)
It is obtained by
Silt content= (V1/V2) x100
V1= Volume of sand layer alone.
V2= volume of Volume of sand below the silt.
12. Fineness modulus of Fine aggregate
Fineness modulus is obtained adding the percentage of the weight of fine aggregate retained on each sieve and dividing by 100.
Fine modulus= cumulative weight of fine aggregate retained on each sieve/100.
13. Important information obtained from the different tests of Fine Aggregates.
- Less than 5% moisture content in the fine aggregate is preferred for construction work.
- If Fine Aggregate having Fineness modulus greater than 3.2, then it is not suitable for concrete.
- Permissible silt content in Fine Aggregate = 6%.
14. Moisture content and Percentage of bulking with respect to volume
|S.No.||% Moisture content||% Bulking w.r.t. Bulking|
15. Characteristics of good quality of Fine Aggregate
- Habitats, Vegetable matter, grass, etc which affect the setting and binding property of concrete.
- It should be chemically inert.
- Fine Aggregate should be free from silt and clay.
- Fine Aggregates should not contain more than 3 percent of silt.
- It should not contain salts that contain sodium chloride that causes corrosion to reinforcement.