A very cohesive soil includes a large percentage of ________.

A very cohesive soil includes a large percentage of ________.

• A. Sand
• B. Silt
• C. Clay
• D. Gravel

Answer: (C)

High clay content gives soil its cohesion. Clay has very fine, plate-like particles that bond together and hold water between layers, creating internal attraction that makes the soil stick together and behave plastically when wet. This internal bonding—cohesion—is what makes a soil very cohesive. Sand and gravel are coarse and rely on friction and interlocking rather than bonding, so they don’t contribute to cohesion. Silt can be somewhat cohesive, but not as strongly as clay. So, a very cohesive soil includes a large percentage of clay.

High clay content gives soil its cohesion. Clay has very fine, plate-like particles that bond together and hold water between layers, creating internal attraction that makes the soil stick together and behave plastically when wet. This internal bonding—cohesion—is what makes a soil very cohesive. Sand and gravel are coarse and rely on friction and interlocking rather than bonding, so they don’t contribute to cohesion. Silt can be somewhat cohesive, but not as strongly as clay. So, a very cohesive soil includes a large percentage of clay.