Sand is a basic raw material used in the construction industries. It is fine aggregate having the particle size between 150 microns and 4.75 mm. Silt content is a super fine material which is less than 150 microns / 0.15 mm in Size. The slit content should not be more than 6% of the total volume of the sand.
Tests for finding quality of sand on site
Excessive clay / Silt
Presence of clay in Sand makes the sand cohesive, the good quality of sand should have less percentage of clay in it.
Presence of excessive clay can be determined in two ways
- For the testing, the presence of clay in the sand, take a glassful of water and add some sand to it. Shake it vigorously and allow the sand to settle. Check whether an apparent layer is formed on the sand. Good quality of sand should have less than 8% of clay in it.
- Hold some dry sand and drop it. If the Sand adheres to your palm, then it has Clay.
Presence of Organic Impurities in Sand
For detecting the presence of Organic impurities in fine aggregate. Take a Sample of sand and add it in Sodium Hydroxide [NaOH] Solution, Stir the solution for few minutes, if the color of solution changes to brown, then the sand has organic impurities which are not suitable for construction. Good quality of sand shows a lighter color when it is mixed with NaOH solution.
Presence of Excessive moisture content / Bulking of Sand
Presence of excessive moisture content in sand causes increases in the volume of sand. Fine Aggregate Which contains more than 5% of moisture content in its volume is not suitable for construction purposes. For accurate conclusions, fineness modulus test and salt content by weight are suggested for large projects.