What does the Atterberg limits test measure?

The Atterberg limits test measures the plasticity characteristics of fine-grained soils. This test defines the consistency and behavior of soil at different moisture contents, particularly focusing on the transition between the solid, plastic, and liquid states of soil. It specifically helps in determining the water content at which soil changes from a plastic state (capable of being molded) to a liquid state (flowing) and vice versa.

Understanding the plasticity index, which is derived from the Atterberg limits, is crucial for evaluating how a soil will behave under varying moisture conditions, which directly impacts its engineering properties such as strength and compressibility. This test is particularly relevant for fine-grained soils, such as clays, where plasticity plays a significant role in the soil's performance and stability in construction.

This is why the Atterberg limits test is specifically associated with fine-grained soils, making it the focus of option B. The other options pertain to different soil properties that are not addressed by the Atterberg limits test.