Tests for bricks :
A brick is generally subjected to following tests to find out its suitability of the construction work.
ii. Absorption
iii. Crushing strength or compression strength
iv. Hardness
v. Presence soluble salts
vi. Shape and size
vii. Soundness
viii. Structure
1) Absorption: A good should not absorb not more than 20 percent of weight of dry brick
2) Compressive strength: crushing or compressive strength of brick is found out by placing it in compression testing machine. It is pressed till it breaks. Minimum crushing strength of brick is 35kg/cm²and for superior bricks, it may vary from 70 to 140 kg/cm².
3) Hardness: No impression is left on the surface the brick is treated to be sufficiently hard
4) Presence of soluble salts: The bricks should not show any grey or white deposits after immersed in water for 24 hours.
5) Shape and size: It should be standard size and shape with sharp edges.
6) Soundness: The brick should give clear ringing sound struck each other.
7) Structure: The structure should be homogeneous, compact and free from any defects.
Grading of Bricks
As per IS10719557 and 1970 code specifications,
a. Bricks with compressive strength not less than 140kg/cm² – Grade A-A class.
b. Bricks with compressive strength not less than 105kg/cm² – First class bricks - Grade A.
c. Bricks with compressive strength not less than 70kg/cm² – Second class bricks – Grade B.
d. Bricks with compressive strength not less than the average value 35kg/cm² – class III bricks – Grade C.
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