Composite geomembrane (composite impermeable membrane) is divided into one fabric one membrane and two fabrics one membrane, with a width of 4-6m. Depending on the specifications, the weight varies, generally ranging from 200 to 1500g/m2. It exhibits high physical and mechanical performance indicators such as tensile strength, tear resistance, and puncture resistance. The product features high strength, good elongation properties, large deformation modulus, resistance to acids, alkalis, and corrosion, aging resistance, and excellent impermeability. It meets the needs of civil engineering in water conservancy, municipal engineering, construction, transportation, subways, tunnels, and engineering construction for impermeability, isolation, reinforcement, crack prevention, and strengthening. It is commonly used for impermeable treatment of dams and drainage ditches, as well as pollution prevention in waste disposal sites.

Composite geomembrane is formed by heating one or both sides of the film with far-infrared radiation in an oven and pressing the geotextile and geomembrane together through guide rollers to create the composite geomembrane. With advancements in production technology, there is also a casting method for producing composite geomembranes. Its forms include one fabric one membrane, two fabrics one membrane, and two membranes one fabric.

Geotextile serves as a protective layer for the geomembrane, preventing damage to the impermeable layer. To reduce ultraviolet exposure and enhance aging resistance, it is best to use the buried method for laying.

During construction, first level the base surface with small-diameter sand or clay, and then lay the geomembrane. The geomembrane should not be stretched too tightly; the parts buried at both ends should be wavy. Subsequently, lay a transition layer of about 10cm with fine sand or clay on top of the geomembrane. Then, lay 20-30cm of block stones (or concrete prefabricated blocks) as an anti-scour protective layer. During construction, efforts should be made to avoid direct impact of stones on the geomembrane. It is best to carry out the protective layer construction simultaneously with the membrane laying. The connection between the composite geomembrane and surrounding structures should be anchored with expansion bolts and steel plate strips, and the connection area should be coated with emulsified asphalt (2mm thick) for adhesion to prevent leakage at that point.

Construction Considerations

(1) The buried method must be used: the coverage thickness should not be less than 30cm. Composite geomembranes are widely used in reservoir impermeability projects.

(2) The impermeable system should consist of: a cushion layer, an impermeable layer, a transition layer, and a protective layer.

(3) The soil should be firm to avoid uneven settlement and cracks. Grass and tree roots within the impermeable range should be removed. A protective layer of small-diameter sand or clay should be laid on the surface in contact with the membrane.

(4) During laying, the geomembrane should not be pulled too tightly. It is better for the parts buried at both ends to be wavy, especially when anchoring with rigid materials, allowing for some伸縮量 (expansion and contraction).

(5) During construction, avoid direct impact of stones and heavy objects on the geomembrane. It is best to carry out construction, membrane laying, and protective layer covering simultaneously.