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Q: The maximum amount of dust which may be permitted in aggregates is
  • A. 5% of the total aggregates for low workability with a coarse grading
  • B. 10% of the total aggregates for low workability with a fine grading
  • C. 20% of the total aggregates for a mix having high workability with fine grading
  • D. All option are correct
Correct Answer: Option D - • The sum of the percentage of all deleterious material shall not exceed 5%. Fine aggregate must be checked for organic impurities such as decayed vegetation humps, coal dust etc. • Aggregates should not contain any harmful material in such a quantity so as to affect the strength and durability of the concrete. & 20% of total aggregates for a mix having high workability with fine grading is amount of dust permitted in aggregate.
D. • The sum of the percentage of all deleterious material shall not exceed 5%. Fine aggregate must be checked for organic impurities such as decayed vegetation humps, coal dust etc. • Aggregates should not contain any harmful material in such a quantity so as to affect the strength and durability of the concrete. & 20% of total aggregates for a mix having high workability with fine grading is amount of dust permitted in aggregate.

Explanations:

• The sum of the percentage of all deleterious material shall not exceed 5%. Fine aggregate must be checked for organic impurities such as decayed vegetation humps, coal dust etc. • Aggregates should not contain any harmful material in such a quantity so as to affect the strength and durability of the concrete. & 20% of total aggregates for a mix having high workability with fine grading is amount of dust permitted in aggregate.