详细内容：
Natural bentonite is mainly classified into two categories based on chemical composition: sodium-based and calcium-based. Bentonite has the property of swelling upon contact with water. Generally, when calcium-based bentonite swells, its expansion is only about three times its own volume. When sodium-based bentonite expands, it is about 15 times its own volume and can absorb 6 times its own weight in water. The high-density colloid formed by such expanded bentonite has the property of repelling water. The bentonite anti-seepage pad made by the needle-punching method can form many small fiber Spaces, preventing bentonite particles from flowing in one direction. When exposed to water, it forms a uniform and high-density gel-like waterproof layer inside the pad, effectively preventing water leakage. It is mainly used for artificial lake water features, landfill sites and underground garages.