Bentonite is a type of clay that is the primary constituent of drilling fluid. Its properties make it suitable for keeping ground cuttings in suspension so that they can be pumped to the surface. It is also used to lubricate the cutting head, thus, reducing wear and lubricating the tunnel walls, making it easier for pipes to be installed.
Trenchlesspedia Explains Bentonite
Bentonite clay obtains its properties from the mineral montmorillonite. When combined with water, bentonite swells and increases its volume many times over. The harsh conditions of trenchless construction where equipment is subject to severe environmental pressure and mechanical stress are eased with the use of bentonite due to its lubrication properties. Bentonite is produced in quarries after which it is processed and dried. It is mixed with water and other additives at the trenchless drilling site. Used drilling fluid can be cleaned and recycled, minimizing waste and expensive disposal costs.