A clay whose shear strength is decreased to a fraction of its former value by remolding is called?

• A. A stiff clay
• B. A clay with high plasticity
• C. A clay binder
• D. A sensitive soil

Answer: (D)

This item centers on the concept of sensitivity in clays—the change in shear strength when the soil is disturbed or remolded. Some clays retain most of their strength after disturbance, while others lose a large portion of their strength when the structure is broken up. When remolding reduces the shear strength to only a fraction of its undisturbed value, the soil is called a sensitive soil. The degree of sensitivity is described by the ratio of undisturbed shear strength to remolded shear strength; a higher ratio means more sensitivity. This matters in practice because highly sensitive clays can weaken dramatically during construction, excavation, or seismic shaking, leading to instability. For example, if a clay has an undisturbed strength of 100 kPa and remolds to 25 kPa, its sensitivity is 4, indicating a highly sensitive soil. The other options describe stiffness, plasticity, or an unrelated term, not the remolding-induced strength loss that defines sensitive soils.