Shrink–swell capacity

The shrink–swell capacity of soils refers to the extent certain clay minerals will expand when wet and retract when dry. Soil with a high shrink–swell capacity is problematic and is known as shrink–swell soil, or expansive soil.[1] The amount of certain clay minerals that are present, such as montmorillonite and smectite, directly affects the shrink-swell capacity of soil.[2] This ability to drastically change volume can cause damage to existing structures, such as cracks in foundations or the walls of swimming pools.[3]