Sand and its Sources.
This video deals with sand and different natural sources of sand.
Sand is an important building material which abundantly occurs in nature and is formed by decomposition of the rocks.
Generally, sand particles consist of small grains of silica (SiO2).
Sand is the chief ingredient in lime mortar, cement mortar, concrete etc.
Let us now see about natural sources of sand.
As sand are formed by weathering of rocks, sources of sand denote for which it is available.
They are:
Pit sand
River sand
And
Sea sand
Pit Sand:
These sands are obtained by forming pits in soils.
The pit is excavated to a depth of 2 m from the ground level.
The sands lying below this is taken for construction purpose.
It consists of sharp granular grains which are free from salts.
However, pit sand consists of clay, iron oxide and organic matter which should be removed before using.
Pit sand is suitable for mortar or concrete works.
River sand:
It is obtained from the beds or banks of rivers.
It consists of fine rounded grain which is formed by mutual attrition under the action of water.
Generally, river sand is almost white in colour and are available in clean condition.
River sand is suitable for all construction works.
Sea Sand:
This sand is obtained from sea shores which consist of fine rounded grains like river sand.
The sea sand contains salts which attracts moisture from atmosphere.
This absorption will lead to disintegration, efflorescence and dampness.
Apart from this, sea sand increases the setting time of cement.
Thus, it should be avoided for construction purpose.
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