The geomembrane for seepage prevention includes two aspects: first, environmental stress crack resistance, meaning that HDPE geomembrane can crack due to external environmental radiation, ultraviolet light exposure, wind, and damage from hard, sharp objects; second, antioxidant induction time, referring to the oxidation time of HDPE geomembrane under various uncontrollable factors. The welding methods for HDPE geomembrane: 1. The temperature, speed, and pressure for welding are determined after experimental and testing. 2. Stop welding when the environmental temperature is too high or too low. 3. The welding rod should match the membrane material. 4. Each piece of geomembrane is welded on the day of laying. 5. The weld seam at the edge of the upper geomembrane should be ground to a 45-degree angle to ensure welding quality. 6. During hot melt welding, the overlap width should be no less than 15 centimeters. 7. The thickness of the welding area should not be less than 1.2 times the membrane thickness. 8. When flattening the overlap, the overlap should be no less than 10 centimeters when trimming the皱纹 of the creased edges. 9. Avoid cross overlaps and use a T-intersection welding pattern.

Geosynthetic membranes, widely used in various projects such as road construction, farming, and water conservancy, primarily serve as waterproofing and seepage prevention. To meet the usage standards of different projects, a variety of specifications of geosynthetic membranes have emerged in the market, including LDPE and HDPE membranes. So, what are the raw materials for these geosynthetic membranes?

Raw Materials for Waterproof Geomembrane

Regardless of the type of geomembrane, its essence is a polyethylene plastic film, primarily composed of polyethylene (PE), ethylene/copolymer (EVA), and others, all of which are molecularly flexible materials.

HDPE geomembrane, also known as high-density polyethylene geomembrane, boasts excellent heat and cold resistance. Additionally, it has good chemical stability, capable of withstanding the corrosion from strong acids, bases, and oils, and provides excellent seepage coefficient.

2. LDPE geomembrane, or low-density polyethylene geomembrane, may not perform as well as HDPE geomembrane in certain aspects, but it boasts superior aging resistance and environmental stress cracking resistance compared to HDPE geomembrane.

Category of Raw Materials for Waterproof Geomembranes

Geotextile raw materials are categorized into recycled materials and virgin materials. Recycled materials, also known as reclaimed materials, include flower material, second-grade material, first-grade material, and good green material; while virgin materials, also referred to as new materials, are derived from crude oil. New materials have greater toughness and strength compared to recycled materials.

1. New Material

The new material is moisture-free, crystal clear, and bright white, so no additional materials, such as desiccants or colorants, are needed during the production of film from the new material. The new material also does not require heating and drying in a mixing dryer. The new material is generally divided into linear low-density polyethylene resin and high-density polyethylene resin, with the latter commonly referred to as low-pressure. Geotextiles made from linear low-density polyethylene resin can reach a strength of 27 mPa, typically known as smooth surface geotextiles; those made from low-pressure material are generally used for construction projects.

2. Recycled Materials

Membranes made from premium-grade materials are referred to as "Grade A White." High-quality Grade A materials can produce geomembranes with a strength of up to 20 mPa. Grade B materials can be mixed with greenhouse materials (good green materials) in a certain ratio. Due to variations in raw material suppliers, production technologies, and brand names, the ratio of Grade B to greenhouse materials may change. Generally, geomembranes produced with a 7:3 ratio of Grade B to greenhouse materials can achieve a strength of 17 mPa; geomembranes produced with a 5:5 ratio of Grade B to greenhouse materials typically reach a strength of 14 mPa.

The geotextile membrane produced from recycled materials using flower material as the raw material does not meet the 14mPa strength requirement, which we commonly refer to as the enterprise standard. Flower material is usually mixed with greenhouse material to produce geotextile membranes. Due to the moisture and impurities in the recycled materials, moisture absorbent and colorant must be added when using first-grade, second-grade, good green, and flower materials as raw materials. Colorants are divided into double-resistant and regular colorants, with the double-resistant colorant being black, and the regular colorant coming in black, porcelain white, and bright white varieties. Adding double-resistant colorant can enhance resistance to ultraviolet rays and oxidation aging, resulting in a membrane with a longer lifespan and greater durability.