What are the Natural sources of sand?
- Pit Sand
- River Sand
- Sea Sand
What is Pit Sand?
Pit sand consists of sharp angular grains that are free from salts for creating mortar, clean pit sand free from organic and clay should only be used.This sand is found as deposits in soil and it’s obtained by forming pits to a depth of regarding one meter to two meter from the bottom level.
What is River Sand?
This sand is obtained from beds of rivers, River sand consists of fine rounded grains. Colour of river sand is nearly white. As the river sand is sometimes available in clean condition, it’s widely used for all purposes.
What is Sea Sand?
This sand is obtained from sea shores. Sea sand consists of rounded grains in brown colour. Sea sand consists of salts which are a magnet for moisture from the atmosphere and causes dampness, efflorescence and disintegration of work. Due to all such reasons, sea sand isn’t recommendable for engineering works. However, be used as an area material after being thoroughly washed to get rid of the salts.
Characteristics of good sand
- It should be chemically inert.
- It should be clean and coarse.
- It should be free from organic matter.
- It should contain sharp, angular and tough grains.
- It shouldn’t contain salts, which magnetize moisture from the atmosphere.
- It should be graded (i.e.) should contain particles of varied sizes in suitable proportions.
What is the grading of sand?
According to the positioning of grains, sand is classed as fine, coarse and gravelly Sand passing through a screen with clear opening of 1.5875mm is known as fine sand. it’s generally used for masonry work. Sand passing through a screen with clear openings of 7.62mm is known as gravelly sand. it’s generally used for plastering. Sand passing through a screen with clear opening of 3.175mm is known as coarse sand. it’s generally used for masonry work.
What is bulking of sand?
The presence of moisture in sand increases the quantity of sand. this is often thanks to incontrovertible fact that moisture causes film of water around the sand particles which result in the rise of volume of sand.
For a moisture content of 5 to 8 percent, the rise in volume could also be about 5 to 8 percent, depending upon the grading of sand. The finer the material, the more are going to be the increase in volume for a given moisture content. This phenomenon is understood as bulking of sand. When moisture content is increased by adding more water, sand particles pack near one another and therefore the amount of bulking of sand is decreased.
Thus, the dry sand and also the sand completely flooded with water have practically constant volume. for locating the bulking of sand, a test is applied with the following procedure
- A container is taken and it’s filled two third with the sample of sand to be tested.
- The height is measured, say 20cm.
- Sand is taken out of container
- The container is full of water
- Sand is then slowly dropped within the container and it’s thoroughly stirred by means of a rod.
- The height of sand is measured say 16cm, then bulking of sand or (20-16)/20 =4/16 or 25%