With the increase in compaction energy in a compaction test
- AMaximum Dry Density and Optimum Moisture Content both increase
- BMaximum Dry Density increases and Optimum Moisture Content decreasesCorrect
- CMaximum Dry Density and Optimum Moisture Content both decrease
- DMaximum Dry Density decreases and Optimum Moisture Content increases
Solution
Concept
More compaction energy packs particles closer, so the curve shifts up and to the left.
Step-by-step solution
1. Compare the Standard Proctor and Modified Proctor tests. 2. The Modified Proctor test uses more energy per unit volume. 3. Its compaction curve lies above and to the left of the standard curve. 4. So MDD increases and OMC decreases.
Explanation
With higher compaction energy, soil particles come closer even at lower water content. So the maximum dry density increases. Less water is needed to reach it, so the optimum moisture content decreases.
Why the other options are wrong
A: OMC does not increase; it decreases. C: MDD does not decrease; it increases. D: This is the exact opposite of the real effect.
Shortcut
More energy: curve moves up and left (MDD up, OMC down).
Common mistake
Thinking more energy needs more water. In fact, less water is needed.
Correct answer: B) Maximum Dry Density increases and Optimum Moisture Content decreases