Bentonite

Definition

Bentonite is a type of clay composed principally of minerals from the montmorillonite group. It is characterized by high absorption and significant volume changes when wet or dry, commonly swelling to several times its dry volume when saturated with liquid.

Purpose

Bentonite is widely used in various industries due to its unique properties of swelling, absorption, and plasticity. In construction, bentonite is often used as a sealing material in geotechnical engineering to prevent water seepage. It is also used in drilling mud to lubricate and cool cutting tools, remove cuttings, and stabilize boreholes in oil and gas exploration. Additionally, bentonite is utilized in foundries, paper manufacturing, and as a binding agent in the production of iron ore pellets.

Examples of Use

1. Geotechnical Engineering: Bentonite is used to create impermeable barriers in landfills, ponds, and underground storage facilities to prevent contamination of groundwater.
2. Drilling Operations: In oil and gas exploration, bentonite-based drilling mud is used to stabilize boreholes and facilitate the removal of drill cuttings.
3. Foundry Molding: Bentonite is mixed with sand to create molds for metal casting, providing shape and stability during the casting process.
4. Civil Engineering: Bentonite slurry is used in the construction of diaphragm walls for deep excavations and tunnels.

Related Terms

1. Montmorillonite: The primary mineral component of bentonite, responsible for its swelling properties.
2. Clay: A natural, fine-grained soil material that can exhibit plasticity and cohesion.
3. Drilling Mud: A fluid mixture used in drilling operations to lubricate the drill bit, transport cuttings, and stabilize the borehole.
4. Sealing Material: Substances used to prevent the passage of fluids through surfaces or joints.
5. Geosynthetic Clay Liner: A manufactured product that combines bentonite clay with geotextiles to provide a barrier for containment applications.

Notes

• Bentonite's properties can vary depending on its source and the specific type of montmorillonite present.
• Proper handling and hydration of bentonite are crucial to achieve its desired properties in various applications.
• Environmental regulations often dictate the use of bentonite in containment systems to protect groundwater quality.