What is the difference between cohesive and non-cohesive soils?

Cohesive soils are characterized by their fine particles, which include clay and silt, that can adhere to one another due to intermolecular forces. This property allows cohesive soils to maintain their shape and resist deformation when wet, making them cohesive in nature. On the other hand, non-cohesive soils, such as sand and gravel, comprise larger particles that do not stick together. The loose particle structure of non-cohesive soils means they tend to drain quickly and occupy a more unstable state when wet. This fundamental distinction is crucial for understanding soil behavior, especially in fields like construction and geotechnical engineering, where the choice of soil impacts stability, compaction, and overall project success.