GCL (Geotextile Clay Liner) is a specialized geosynthetic material used for preventing leakage in artificial lakes, landfill sites, underground parking garages, rooftop gardens, ponds, oil storage facilities, and chemical storage yards. The GCL is filled with highly expansive sodium bentonite between a custom composite geotextile and nonwoven fabric. The needle-punched bentonite liner forms numerous small fiber spaces, preventing the bentonite particles from flowing in one direction. When water is present, it creates a uniform, high-density gel-like waterproof layer within the pad, effectively preventing water leakage.

I. Description

GCL is a type of waterproofing liner that falls between GCL (in-situ thick compacted clay waterproofing liner) and geomembrane materials. It is primarily used in environmental engineering projects such as waste landfill sites, underground reservoirs, and underground infrastructure construction, addressing issues of sealing, isolation, and leakage prevention, with excellent performance and strong resistance to damage.

II. Principle

The mineralogical name for bentonite is montmorillonite. Natural bentonite is primarily divided into two main categories based on chemical composition: sodium-based and calcium-based. Bentonite has the property of expanding when it comes into contact with water. Generally, calcium-based bentonite expands to about three times its original volume. When sodium-based bentonite is locked between two layers of geosynthetic materials, it serves as a protective and reinforcing agent, giving the GCL a certain overall shear strength.

Section 3: Characteristics of Bentonite Waterproofing

Integrity: Sodium-based bentonite forms a high-density diaphragm under hydraulic pressure. At a thickness of approximately 3mm, its permeability is below &×10ˉ11m/sec, equivalent to the compactness of 100 times that of 30cm-thick clay, and it possesses strong self-water-retaining properties.

2. Features permanent waterproofing: As sodium bentonite is a natural inorganic material, it does not undergo aging or corrosion even after a long time or changes in the surrounding environment, ensuring long-lasting waterproofing properties.

3. Easy installation and short construction period: Compared to other waterproofing materials, the installation process is relatively simple and does not require heating or adhesive application. Just connect and secure with bentonite powder, nails, washers, etc. No special inspection is needed after installation, and any waterproofing defects are easy to repair. GCL has one of the shortest construction periods among existing waterproofing materials.

4. Temperature-Resistant: Will not crack under cold weather conditions.

5. Integrated Waterproofing Materials and Objects: Sodium bentonite has an expansion capacity of 20-28 times when encountering water. Even if concrete structures undergo vibration and settlement, the bentonite within the GCL can repair cracks on the concrete surface up to 2mm in width.

6. Eco-Friendly: Bentonite is a natural inorganic material, harmless to humans and the environment, with no significant impact on the environment and excellent eco-friendly properties.

Section 4: Product Technical Specifications:

Serial Number Inspection Item Unit Inspection Standards and Requirements

1.膨润土膨胀系数 ml/2g ≥ 24

2 GCL Units Area Weight g/m² ≥5000

3 GCL longitudinal tensile strength KN/m ≥10

4 GCL Lateral Fracture Strength KN/m ≥10

5 GCL Longitudinal Tensile Elongation % ≥10

6 GCL Lateral Tensile Stretch Rate % ≥6

7 GCL Vertical Permeability Coefficient cm/s ≤ 5×10^-9

8 GCL Bursting Strength N ≥ 400

9 GCL剥离强度 N/10cm ≥65

10 GCL Hydrostatic Resistance Test 0.3MPa, 30min, No Leakage

V. GCL Connection

The connections between GCLs and between GCLs and structures are both simple, and the sealing at the joints is also very effective.

GCL to GCL connection

1.1 Simple Lap Seam --- Tape Seam

The gcl should be overlapped by 25cm in both length and width (10cm for the main body and 15cm for the edges), ensuring the joints are free of wrinkles, debris, and other materials. At a distance of 25cm, lay a 10cm wide, 1cm high strip of bentonite powder, manually or mechanically, to overlap between the two layers of gcl.

1.2. Mated Joint Sealing - Paste Method

Generally, "tape method" is used directly for laying and sealing at flat seams, while bentonite paste is applied on slopes and special points. (Bentonite paste -- mix water (weight ratio 1:3) with bentonite powder, stir continuously and evenly until a smooth and soft paste is obtained.)

2. GCL connection with pipes and structures

2.1, Apply "strip method" or "paste method" for careful sealing. When connecting to the structure, the gcl ends on the horizontal surface should be meticulously constructed to ensure a seal.

2.2 When laying the geosynthetic clay liner (GCL) on the facade and sloping surfaces, use nails and washers to secure it to prevent slippage. Besides using steel nails to fix the edges of the GCL overlap, the entire middle section of the GCL should also be nailed according to flatness, ensuring the GCL is firmly and securely attached to the wall and floor. If necessary, use clay mortar to bond the GCL to the wall. The nail holes can be treated as needed. See the illustration above for details.

Technical Specifications:

Expanding Waterproof Mat (GCL) Technical Specifications JG/T 193-2006