The moisture content at which a specified amount of compaction produces maximum dry density is known as ______.
Try it first: pick an option, then read the explanation.
Correct answer: A. optimum moisture content
Asked in SSC JE 14/11/2022
Detailed Explanation
The key words are ‘specified amount of compaction’. For one fixed compactive effort, there is exactly one water content that gives the highest dry density. That water content is the optimum moisture content (OMC).
Why “optimum moisture content” Is Correct
The definition is tied to the effort: change the effort and the OMC changes too. That is why the question says ‘a specified amount of compaction’ and why the OMC from light compaction differs from the OMC from heavy compaction.
Why the Other Options Are Wrong
- B. absolute moisture content: ‘Absolute moisture content’ is not a term used to define the compaction peak.
- C. retained moisture content: ‘Retained moisture content’ is not a standard compaction term.
- D. specific moisture content: ‘Specific moisture content’ is not a standard compaction term either.
Key Point
Same soil, more effort → lower OMC and higher MDD. Same effort, different soil → different OMC.
Key Concepts for Students
- The Proctor test finds the OMC and MDD together.
- Field compaction is done at water contents close to the OMC.
- OMC is usually written as a percentage of the dry mass of soil.
Practice more: this is question 11 of Compaction of Soil MCQs – Part 1. Try the whole set and check every answer instantly.