Which Atterberg limit indicates the transition of soil to a liquid state?

• A. Shrinkage Limit
• B. Plastic Limit
• C. Liquid Limit
• D. Non-Plastic Limit

Answer: (C)

The Liquid Limit is the correct choice because it defines the water content at which soil transitions from a plastic state to a liquid state. At this point, the soil behaves like a viscous fluid, which means it cannot support any load without flowing. This limit is determined through the use of a standardized laboratory test, where a soil sample is placed in a cup and subjected to a specified number of blows from a penetrometer until it flows a certain distance. The Liquid Limit is crucial for understanding the consistency and behavior of fine-grained soils under varying moisture conditions.

The Shrinkage Limit marks the point at which soil begins to shrink, indicating the transition from a semi-solid state to a solid state, not a liquid state. The Plastic Limit indicates the moisture content at which soil can be manipulated without breaking apart, representing a shift from a semi-solid state but still not reaching the liquid phase. The Non-Plastic Limit relates to soils that do not exhibit plastic behavior and are not influenced significantly by moisture content, thereby not relevant to identifying a transition to a liquid state.