Bentonite slurry

A Bentonite slurry is a mixture clay and water. One of the main uses is in construction.

Large buildings, for instance, will use a special narrow excavator, which will excavate a narrow hole, that surrounds where the buildings foundations will be. The Bentonite slurry is heavier and denser than water. So, the hole is filled with slurry, as it is dug, and the heavy dense slurry balances the ground pressure that would otherwise force the hole to collapse.

When ready concrete will be poured into the hole. When this process is complete a watertight concrete wall will surround the soil that needs to be dug up to make the foundation.