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Q: What is the main characteristic of fourth class bricks?
  • A. They are light in colour
  • B. They are over burnt and irregular in shape
  • C. They are not used as aggregates for concrete in foundations, floors and roads
  • D. None of the above
Correct Answer: Option B - Quality of brick : First class brick:- Uniform deep red or cherry colour. The surface should be smooth and rectangular with perfect sharp and straight edges water absorption should be 20% of its dry weight, when immersed in cold water for 24 hour. The crushing strength should not be less than 10N/mm2 Second class brick– Requirements as the first class brick except (1) Small cracks and distortion are permitted (2) Water absorption 22% of dry weight (3) Crushing strength should not be less than 7.0 N/mm² Third class brick– They are soft and light coloured producing a dull sound when struck against each other under burnt. • Water absorption is about 25% of dry weight. • Use for building temporary structures. Fourth class bricks– Over burnt brick is badly distorted or irregular in shape and size and are brittle in nature. • Used for foundation and floors in lime concrete and road metal.
B. Quality of brick : First class brick:- Uniform deep red or cherry colour. The surface should be smooth and rectangular with perfect sharp and straight edges water absorption should be 20% of its dry weight, when immersed in cold water for 24 hour. The crushing strength should not be less than 10N/mm2 Second class brick– Requirements as the first class brick except (1) Small cracks and distortion are permitted (2) Water absorption 22% of dry weight (3) Crushing strength should not be less than 7.0 N/mm² Third class brick– They are soft and light coloured producing a dull sound when struck against each other under burnt. • Water absorption is about 25% of dry weight. • Use for building temporary structures. Fourth class bricks– Over burnt brick is badly distorted or irregular in shape and size and are brittle in nature. • Used for foundation and floors in lime concrete and road metal.

Explanations:

Quality of brick : First class brick:- Uniform deep red or cherry colour. The surface should be smooth and rectangular with perfect sharp and straight edges water absorption should be 20% of its dry weight, when immersed in cold water for 24 hour. The crushing strength should not be less than 10N/mm2 Second class brick– Requirements as the first class brick except (1) Small cracks and distortion are permitted (2) Water absorption 22% of dry weight (3) Crushing strength should not be less than 7.0 N/mm² Third class brick– They are soft and light coloured producing a dull sound when struck against each other under burnt. • Water absorption is about 25% of dry weight. • Use for building temporary structures. Fourth class bricks– Over burnt brick is badly distorted or irregular in shape and size and are brittle in nature. • Used for foundation and floors in lime concrete and road metal.