Compressive /Crushing Strength of Bricks

Compressive /Crushing strength of  bricks (Indian Made) are very variable, and may vary from 30 kg/sq. cm to 150 kg/sq. cm for hand-made burnt bricks, while Crushing strength of  heavy duty bricks machine pressed (also called engineering bricks) may have compressive strength as high as 450 kg/sq. cm, and even 500 kg/sq. cm. The minimum crushing / compressive  strengths of burnt bricks tested flat-wise prescribed are:

(i) Common building bricks—35 kg/sq. cm,

(ii) Second class bricks—70 kg/sq. cm,

(iii) First class bricks— 105 kg/sq. cm.

(iv) Crushing strength of bricks not less than 140 kg/sq. cm are graded as AA class.

The strength of  bricks decreases by about 25 per cent when soaked in water.

Strength of sun-dried (unburnt) bricks is from 15 to 25 kg/sq. cm.

Water absorption of bricks after 24 hours immersion,

First class bricks—20%,

Second class bricks—22 %,

Third class bricks—25%.

Heavy duty machine made bricks should not absorb more than 5% of their weight.