What does the term "plasticity" refer to in soil science?

• A. Ability of soil to resist deformation
• B. Ability of soil to behave as a solid
• C. Ability of soil to undergo deformation at a constant volume
• D. Ability of soil to remain unchanged

Answer: (C)

In soil science, "plasticity" refers to the ability of soil to undergo deformation at a constant volume when subjected to an applied stress. This property is essential in understanding how soils behave under various conditions, particularly when they are subject to forces such as load from structures or during changes in moisture content. Soils that exhibit plastic behavior can change shape without experiencing a change in volume, which allows them to accommodate stresses without fracturing.

This characteristic is particularly important in the context of construction and earthwork, as it directly influences the stability and performance of soils used in building foundations, roads, and other infrastructure. Plasticity is typically assessed through tests such as the Atterberg limits, which help determine the moisture content at which soil transitions between different states (solid, plastic, and liquid).

The other options misconstrue the concept of plasticity. Resistance to deformation, behaving as a solid, and remaining unchanged are attributes related to other aspects of material behavior, like rigidity or cohesion, but do not accurately capture the essence of plasticity in soils.