Which type of soil will experience the most increase in volume when excavated?

Clay is the type of soil that will experience the most increase in volume when excavated. This phenomenon is largely due to the unique properties of clay particles, which are very small and compact when in their natural state. Upon excavation, clay can retain moisture, leading to swelling and an increase in volume.

Additionally, clay has a high plasticity, meaning it can change shape under pressure and can hold onto water, which further contributes to its tendency to expand significantly. This swelling behavior is particularly relevant in construction and excavation projects, where managing the volume change of clay is crucial to ensure stability and proper engineering practices.

In contrast, sand consists of larger, more granular particles that do not retain water in the same way clay does, resulting in minimal volume change when excavated. Silt, while also fine-grained, does not swell as dramatically as clay does. Granite, being a solid rock, does not exhibit volume change in the same manner as soil types; instead, it may break or fracture during excavation without experiencing comparable swelling.