Question

In laboratory compaction tests, the optimum moisture content of soil decreases

• A. with increase of compaction energy and with decrease of coarse grains in the soil
• B. with decrease of compaction energy and with increase of coarse grains in the soil
• C. with increase of both compaction energy and coarse grains in the soil
• D. with decrease of both compaction energy and coarse grains in the soil.

Answer 1

The correct option is C with increase of both compaction energy and coarse grains in the soil

As the grain size increases, specific surface area of solids decreases so less water is required to make lubricating water layer around soil particles hence OMC decreases. As compactive effort increases the OMC decreases.