What is the difference between bentonite grout and neat cement grout in well sealing?

What is the difference between bentonite grout and neat cement grout in well sealing?

• A. Bentonite grout is clay-based and highly swelling, creating a low-permeability seal; neat cement grout is cement-based and provides a rigid, durable seal.
• B. Bentonite grout is more permanent and hard; neat cement grout is flexible.
• C. Bentonite grout is water-absorbent and cement grout is not.
• D. Bentonite is used above ground, cement is used below ground.

Answer: (D)