1. Which one of the following is not an advantage of using M-sand?
a) Cost effective
b) Available in single size
c) Dust and impurity free
d) Can be obtained from hard rock
Discussion
Explanation: M-sand is obtained by crushing specific hard rock and since it’s manufactured in factories, any size can be manufactured depending on the need.
2. What is the meaning of bulking of sand?
a) Increase in volume of sand due to moisture absorption
b) Increase in weight of sand due to moisture absorption
c) Increase in mass of sand due to moisture absorption
d) Increase in strength of sand due to moisture absorption
Discussion
Explanation: When water is added to sand, a thin film of water is formed around the sand particles. The film exerts surface tension on particles, making them move apart. This leads to an increase in volume because there is no direct contact among particles.
3. How is bulking related to moisture content?
a) Keeps on increasing with moisture content
b) Increases to a certain point and then decreases
c) Keeps on decreasing with moisture content
d) Decreases to a certain point and then increases
Discussion
Explanation: The volume i.e. bulking increases as sand absorbs moisture. At about 6- 10%, the film starts breaking and the volume reduces. If sand absorbs further moisture, no bulking takes place.
4. What happens if bulking is not accounted for while preparing concrete?
a) Concrete gets hardened
b) Concrete is not affected
c) Concrete gets softened
d) Concrete becomes watery
Discussion
Explanation: If care is not taken while volume batching, concrete is likely to be undersanded and gets hard eventually.
5. By how much percentage does the volume increase when the moisture content is 5-10%?
a) 10-20%
b) 20-40%
c) 30-40%
d) 20-30%
Discussion
Explanation: The studies on bulking have shown this result. It is visible in the graphical representation of bulking also.
6. How is particle size of sand related to bulking?
a) Not related
b) Directly proportional
c) Inversely proportional
d) Shows variable relation
Discussion
Explanation: Finer particle size will have more voids compared to coarser once. They tend to absorb more water and hence exhibit more bulking.
7. What does ‘h’ represents in the formula used to calculate the bulking factor?
a) Height of jar
b) Height of saturated sample
c) Height of dry sample
d) Height of water
Discussion
Explanation: The formula used to calculate bulking factor is (H-h/h) x 100%. ‘H’ represents height to which dry sand sample is filled in jar and ‘h’ represents the height of the saturated sample.
8. Bulking is the phenomenon applicable to both fine and coarse aggregates.
a) True
b) False
Discussion
Explanation: Bulking is possible only in fine aggregates. In coarse aggregate, size of particle is large, void space is less and so water absorption is not possible up to the extent of fine aggregates.
9. Sand does not show any bulking when:
a) Completely saturated
b) Partially saturated
c) Contains small amount of impurities
d) Voids are partially filled with air
Discussion
Explanation: A completely saturated sand has no void space left to absorb any more water and undergo bulking.
10. What effect does bulking have on fresh concrete?
a) Strength reduces
b) Shrinkage increases
c) Volume reduces
d) Workability increases
Discussion
Explanation: The excess water in the sand can be used to maintain water-cement ratio. It improves workability and hence it is easier to place fresh concrete. Strength is a property of hardened concrete.