What defines the ability of soil to stick together when dry and is influenced by plasticity when wet?

The ability of soil to stick together when dry and its responsiveness to plasticity when wet is best defined by cohesion. This refers to the attractive forces between particles within the soil that help maintain its structure. When soil is dry, cohesive forces allow particles to hold together, creating a stable mass. When moisture is introduced, the plasticity of the soil can change, affecting its cohesiveness. Plasticity describes the degree to which soil can be molded or shaped when wet, but cohesion is the critical factor that explains how the soil maintains structural integrity both in dry and wet conditions.

This concept is particularly significant in understanding how various soil types behave under different moisture levels and mechanical stresses, which is essential for construction and earthworks. Cohesion plays a vital role in assessing soil stability, making it a key focus in geotechnical engineering and surveying practices.