DFIFFERENT TYPES OF SAND USED IN CIVIL CONSTRUCTIONS

credit: george hill timber.co.uk

Hello friends, Today I want to write my blog about one of the inorganic substance which is play a important roll in our subject. It is "SAND". You all know source of sand in our society is river and river bank, pit and sea side. Although sand is get from different sources but all types of sand are not applicable for civil construction work. Some are used in different works, here I stated the different types of sand and their uses in civil construction works, Let us start source of sand
1) River sand
2) Pit sand
3)  Sea sand
Accornding to size sand are classified into three groups:
a) Fine sand
b) Medium sand
c) Coarse sand
Today I discuss about the qualities of sand.

credit:-civilread.com

a) Fine sand:- The size of this types of sand in between 0.6mm to 75 micron, average fineness modulus 2.2 to 2.6, in this type of sand many impurities are mixed, salty impurities are also in it.
For that the impurities causes chemical reaction with the cement and made effect in concrete and mortar, for that this kind of sand only used in filling.

credit:-happho.com

b) Medium sand:- The size of this types of sand in between 2.0mm to0.6mm, and average fineness modulus 2.6 to 2.9. this type of sand mainly used in brick work mortar, inside wall plaster, out side wall plaster, plaster design and flooring. This may also used in pointing.

credit:- civilread.com

c) Coarse sand:- The size of this type of sand i between 2mm to 4.75mm, fineness modulus is 2.9 to 3.2, size of this type of sand is greater than other two type. Thease are mainly used in different types of concrete likr column, tie beam, lintel slab etc.
The quality sand should have some property :
1) Fress, free from impurities.
2) Uniform colour.
3) No hygroscopic petres matter in it.
There have also a important thing of sand and which causes some difficulties of engineers, it is called "BULKING OF SAND".
What is bulking of sand: The increase in volume of dry sand due to absorption of moisture which forms a minimum film of water arround the particles of sand by frictional resistance.
A moisture content of 2% - 5% may increase the volume of sand more than 15% to 30%.
When the moisture content is increase by adding water gradually until the sand is completely saturated, bulking dimishes practically to nil and the sand occupies the least volume  as in the dry state.
The amount of bulking can readily determind at site by suitable method as follows:
Sufficient quantity of sand shall be put loosely  into a container of uniform cross section  levelled off  but not pressed down and its depth is measured. The sand is then well mixed  and stirred with plenty of water and allowed to sattle. The top surface of the inundated sand shall be smoothed and levveled. The new depth of sand is then measured and this is practically equal to that volume which would be occupied by the same weight of sand when dry.Now the amount of loss in the volume of sand is the amount of bulking.

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