Bentonite, a naturally occurring clay mineral, plays a significant role in various industrial and construction applications. In China, there are over 200 domestic bentonite processing enterprises, most of which are small to medium-sized operations. Several mining companies produce more than 10,000 tons annually, with an overall output reaching approximately 200–210 million tons. The total production capacity exceeds 3 million tons, primarily focused on raw or minimally processed products. Provinces such as Liaoning, Hebei, and Zhejiang lead in production capacity.
The output of bentonite ore or coarse powder is estimated at 1.6–1.7 million tons per year, while deep-processed products like sodium-calcium bentonite, activated clay, and organic bentonite account for about 300,000–400,000 tons. Major production areas include Zhejiang, Jilin, Liaoning, Xinjiang, Hebei, Henan, Hubei, and Anhui.
Traditionally, China has relied on less effective waterproofing methods. While some developed countries use advanced bentonite-based waterproofing materials with excellent performance, these are rarely adopted in China due to high costs. Recently, bentonite waterproof blankets have started gaining traction, especially after local production reduced prices to about one-third of imported alternatives. These materials are now widely used in municipal, environmental, water management, transportation, and civil engineering projects, including landfills, sewage treatment plants, and underground structures.
Bentonite waterproof blankets improve the impermeability of irrigation channels, strengthen dams and riverbanks, prevent soil erosion, and reduce risks like piping in levees. They are also used in subway projects, highway roadbeds, bridge foundations, and industrial buildings. Their ability to enhance durability and load-bearing capacity makes them a valuable construction material.
Despite growing usage, China lacks specific national standards for bentonite waterproof blankets. Most manufacturers follow international standards like ASTM D5890 or Korean guidelines. For example, some Sino-Korean joint ventures adhere strictly to Korean specifications, requiring natural sodium-based bentonite. However, the lack of clear Chinese standards means that key parameters like montmorillonite content, water absorption rate, and expansion index are often overlooked.
Geotextiles used in these blankets are subject to various standards globally, and China has issued several relevant regulations in recent years. However, many standards remain outdated or not fully enforced. Domestic manufacturers commonly use either natural or artificially sodium-treated calcium-based bentonite. Artificial sodiumization involves adding sodium carbonate to calcium-based soil, but this method can lead to shorter service life and poor long-term performance.
In the U.S., bentonite must be neutral or slightly alkaline, as higher pH levels can cause rapid degradation. Similarly, artificial sodium-based bentonite may fail within a year if not properly treated. Many natural sodium-based bentonites in China do not meet the required expansion index of over 24, so purification and re-sodium treatment are necessary. Some research institutions, like the Xianyang Non-Metallic Research and Design Institute, have experimented with organic polymers to increase expansion ratios significantly, though these are better suited for specialized applications.
The production process of bentonite waterproof blankets is relatively straightforward, but it requires specialized equipment for raw material treatment. Currently, few Chinese manufacturers have dedicated facilities, with many relying on imported automated lines. Auxiliary materials like waterproof powder, slurry bentonite, and waterproof strips are often produced alongside the main product.
China is rich in bentonite resources, with a wide variety of high-quality deposits. For instance, bentonite from Xiazi Street in Xinjiang is comparable to Wyoming’s. However, quality differences persist due to limitations in purification and deep-processing technology. As awareness of bentonite waterproof blankets grows, their market potential is expected to expand significantly. Continued investment in R&D and improved production techniques will be crucial for maximizing the value of China's natural bentonite resources.
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