How much does bentonite waterproofing cost? - .
Bentonite is an absorbent clay of volcanic origin. It is used for waterproofing purposes due to its ability to expand in contact with water. When bentonite and water touch, the clay expands its volume and turns into a gelatinous mass. As a matter of fact, bentonite can absorb 7 to 10 times its own weight in water.