properties, tests, use of sand in building constructions

1. SAND
Sand is a granular material composed of finely divided rock and mineral particles. It is defined
by size, being finer than gravel and coarser than silt.

2. NATURAL RESOURCES OF SAND
 The following are the three types of natural resources from which the sand obtained
1. Pit sand
2. River sand
3. Sea sand

3. Classification of sand
According to the size of grains, the sand is classified as fine, coarse, gravelly.
 The sand passing through a screen with clear opening of 1.587mm is known as fine
sand. It is mainly used for plastering.
 The sand passing through a screen with clear opening of 3.175mm is known as
coarse sand. It is used for masonry work.
 The sand passing through a screen with clear opening of 7.62mm is known as
gravelly sand. Used for concrete work.

4. Bulking of sand

5. Bulking of sand
 For moisture content 5 to 8 % increase in sand volume maybe as 20 to 40%
depending upon grading sand.
Bulking of sand = (Y1- Y2)/Y2

6. PROPERTIES OF GOOD SAND
 It should be chemically inert.
 It should be clean and course and free from organics and vegetable matter. Usually 3-4% clay
allowed.
 It should contain sharp, angular, coarse and durable grains.
 It should not contain salts which attract moisture from atmosphere.
 It should be well graded i.e. should contain particles of various sizes in suitable proportions.

7. Uses of sand in mortar and concrete
 BULK
 SETTING
 SHRINKAGE
 STRENGHT
 SURFACE AREA

8. TESTS ON SAND
To ascertain the properties of sand the following tests may be carried :
1. A glass of water is taken and some quantity of sand is placed in it. It is then vigorously shaken and allowed to settle.
If clay is present in sand its distinct layer is formed at top of sand.
2. For detecting the organic impurities in sand, the solution of sodium hydroxide or caustic soda is added to the sand
and it is stirred. If color of solution changes to brown, it indicates presence of organic matter.
3. The sand is actually tasted to know the presence of salts.
4. The sand is taken out from a heap and it is rubbed against the fingers. If fingers stained , it indicates the sand
contains earthy matter.
5. The color of sand indicates the purity of sand. The size and sharpness of grains may be examined by touching and by
observing with eye.
6. For knowing fineness, durability, void ratio etc., the sand should be examined by mechanical analysis.