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, construction, transportation, subway, tunnel, 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. The geotextile acts as a protective layer for the geomembrane, preventing damage to the impermeable layer. To reduce ultraviolet exposure and enhance aging resistance, the buried laying method is adopted.

During construction, first, use sand or clay with smaller particle sizes to level the base surface, and then lay the geomembrane. The geomembrane should not be stretched too tightly; the parts buried at both ends should be wavy. On the laid geomembrane, spread a transition layer of about 10cm using fine sand or clay. Then, lay 20-30cm of block stones (or concrete precast blocks) as an anti-scour protective layer. During construction, efforts should be made to avoid direct impact of stones on the geomembrane. The protective layer should be constructed while laying the membrane. The connection between the composite geomembrane and surrounding structures should be anchored using expansion bolts and steel plate strips, and the connection area should be coated with emulsified asphalt (2mm thick) for bonding to prevent leakage at that point.

Construction matters:

(1) It must be installed using the buried method: the covering thickness should not be less than 30cm. Composite geomembrane is used in reservoir impermeability projects.

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

(3) The soil should be compact to avoid uneven settlement and cracks. Grass and tree roots within the impermeable range should be cleared. A protective layer of small-particle 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; the parts buried at both ends should be wavy. When anchoring with rigid materials, allowance for expansion and contraction should be made.

(5) During construction, avoid direct impact of stones and heavy objects on the geomembrane. Construction, membrane laying, and protective layer covering should be carried out simultaneously.