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Q: Based on their physical and mechanical properties, clay bricks are classified into ______ classes.
  • A. one
  • B. four
  • C. six
  • D. two
Correct Answer: Option B - Clay bricks are classified into four class – First class brick– • The crushing strength of the brick should not be less than 10.5 N/mm² • First class clay bricks are red deep in colour • The texture is smooth and the surface should be smooth and rectangular. • There bricks should not absorbs water more than 20% of its own dry weight after 24 hr immersion in water. Second class brick– • They are red deep in colour and surface should be smooth. • In second class bricks small cracks are permitted • These bricks should not absorb water more than 22 percent of its own dry weight after 24 hours immersion in water. • It should have a minimum crushing strength of 7 N/mm² Third class bricks– • These type of bricks are under-burnt. Third class bricks are soft and light color. • Third class brick produce dull sound when strike with each other. • These brick should not absorb water more than 25 percent of its own dry weight after 24 hours immersion in water. • It should have a minimum crushing strength of 3 N/mm². Fourth class bricks– • This classification of bricks is distorted in shape and is over-burnt. • Fourth class brick are brittle in nature.
B. Clay bricks are classified into four class – First class brick– • The crushing strength of the brick should not be less than 10.5 N/mm² • First class clay bricks are red deep in colour • The texture is smooth and the surface should be smooth and rectangular. • There bricks should not absorbs water more than 20% of its own dry weight after 24 hr immersion in water. Second class brick– • They are red deep in colour and surface should be smooth. • In second class bricks small cracks are permitted • These bricks should not absorb water more than 22 percent of its own dry weight after 24 hours immersion in water. • It should have a minimum crushing strength of 7 N/mm² Third class bricks– • These type of bricks are under-burnt. Third class bricks are soft and light color. • Third class brick produce dull sound when strike with each other. • These brick should not absorb water more than 25 percent of its own dry weight after 24 hours immersion in water. • It should have a minimum crushing strength of 3 N/mm². Fourth class bricks– • This classification of bricks is distorted in shape and is over-burnt. • Fourth class brick are brittle in nature.

Explanations:

Clay bricks are classified into four class – First class brick– • The crushing strength of the brick should not be less than 10.5 N/mm² • First class clay bricks are red deep in colour • The texture is smooth and the surface should be smooth and rectangular. • There bricks should not absorbs water more than 20% of its own dry weight after 24 hr immersion in water. Second class brick– • They are red deep in colour and surface should be smooth. • In second class bricks small cracks are permitted • These bricks should not absorb water more than 22 percent of its own dry weight after 24 hours immersion in water. • It should have a minimum crushing strength of 7 N/mm² Third class bricks– • These type of bricks are under-burnt. Third class bricks are soft and light color. • Third class brick produce dull sound when strike with each other. • These brick should not absorb water more than 25 percent of its own dry weight after 24 hours immersion in water. • It should have a minimum crushing strength of 3 N/mm². Fourth class bricks– • This classification of bricks is distorted in shape and is over-burnt. • Fourth class brick are brittle in nature.