In Concrete Mix Design, the term "Bulking of Sand" refers to
- AThe increase in the volume of sand caused by a film of moisture around the particles.Correct
- BThe addition of excess fine aggregates to fill the voids in coarse aggregates.
- CThe process of grading sand using a series of standard sieves.
- DThe chemical reaction between sand and the cement paste.
Solution
Concept
Bulking of Sand
Formula
Percentage Bulking = [(V1 - V2) / V2] × 100
Step-by-step solution
1. Review the given question about the meaning of "Bulking of Sand" in Concrete Mix Design. 2. Recall that bulking occurs when moisture forms a film around sand particles, pushing them apart due to surface tension and increasing the volume. 3. Match this definition with the options provided and select Option (a) as the correct choice.
Explanation
Bulking of sand occurs when moisture forms a thin film around each sand particle. Surface tension pushes the grains apart, causing the overall volume of the sand to expand.
Shortcut
To remember "Bulking of Sand", use the phrase "Water Makes Sand Swell": - Moisture Film: A thin layer of water surrounds each sand particle - Surface Tension: Pushes sand grains apart from each other - Volume Expansion: Leads to a noticeable increase in total volume (peaks around 5-6% moisture content)
Common mistake
A common mistake is selecting option B by confusing the physical concept of "bulking" with adding extra bulk or fine aggregates to fill voids. Another frequent error is choosing option D by mistakenly assuming that bulking involves a chemical reaction with cement paste, rather than being a purely physical expansion caused by surface tension from moisture around the sand particles.
Correct answer: A) The increase in the volume of sand caused by a film of moisture around the particles.