GCL · Geosynthetic Clay Liner · Needle-Punched — Sourced From China
GCL Clay Liner,
Priced By The Gram.
Sold by the metre. Works by the gram. A geosynthetic clay liner is a sandwich: two geotextiles holding a core of bentonite clay that swells shut around any puncture. The waterproofing is the clay — grams per square metre — and grams are exactly what a cheap quote quietly removes. We weigh them back in before you pay.
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What You're Actually Buying
A Self-Healing Sandwich Of Clay
Wet sodium bentonite swells to many times its dry volume. Trapped between two needle-punched geotextiles, that swelling has nowhere to go — so it squeezes itself into a nearly impermeable gel that closes small punctures on its own. It's the only lining product that forgives installation damage.
The needle-punching that ties the sandwich together is what lets it hold on slopes — measured as peel strength. Loading (g/m²), swell index, peel strength: three numbers, and you've specified a GCL.
The Grams Ladder
Loading Decides Performance — And Weight Decides Freight
Real numbers from our loading tables: standard 6 m × 30 m rolls. Notice what happens to the container column — GCL is the one geosynthetic where the ship weighs out before it cubes out.
| Bentonite loading | Typical duty | Roll weight (6×30 m) | One 40'HQ carries |
|---|---|---|---|
| 3,000 g/m² | Ponds, canals, decorative lakes | 540 kg | 9,000 m² · 50 rolls |
| 4,000 g/m² | Reservoirs, secondary containment | 720 kg | 6,660 m² · 37 rolls |
| 4,500 g/m² | Landfill base & caps (common spec) | 810 kg | 5,940 m² · 33 rolls |
| 5,000 g/m² | Landfill, tailings, tougher chemistry | 900 kg | 5,400 m² · 30 rolls |
| 6,000 g/m² | Heavy-duty containment | 1,080 kg | 4,500 m² · 25 rolls |
Every row lands the container at ~27 t — the legal weight limit, not the volume, caps the load. Chinese mills also grade the same loading as "standard-compliant" or not: the tier game lives inside the grams here, which is why we weigh cut samples, not labels.
Get the landed price per m² for my specGrades & Specifications
GCL Bentonite Liner: Every Grade, Every Number
Two requirement tables — GRI-GCL3 (Geosynthetic Institute, ASTM methods), the specification international tenders write, and JG/T 193-2006, the Chinese standard the mill's factory certificate is issued against — by bentonite loading from 4,000 to 6,000 g/m² and by construction: needle-punched GCL-NP as standard, film-laminated GCL-OF and adhesive-bonded GCL-AH to order.
These are required values, not a mill's test result: every quote names the grade, and every batch ships with the certificate against JG/T 193 plus our own swell-index and peel-strength check before loading. Standard roll 6 m × 30 m; the container weight plan (≈ 27 t cap) is run before we quote.
Download the GCL TDS (PDF, 2 pages)
Required properties per GRI-GCL3 (GSI) · Table 1(a)
Reinforced GCLs · S.I. units · min / max are minimum / maximum average values · needle-punched is what we ship as standard · MQC test frequencies per the standard are on the TDS
Swipe sideways for all grades →
| Property | Test method | Unit | Needle-punched (GT-related) | Film-laminated (GM/GF-related) |
|---|---|---|---|---|
| Bentonite swell index (as received) | ASTM D5890 | ml / 2 g | 24 min | 24 min |
| Bentonite fluid loss (as received) | ASTM D5891 | ml | 18 max | 18 max |
| Cap fabric mass — nonwoven / woven | ASTM D5261 | g/m² | 200 / 100 min | 200 / 100 min |
| Carrier fabric mass — nonwoven composite / woven | ASTM D5261 | g/m² | 200 / 100 min | 200 / 100 min |
| Mass of GCL, oven-dry | ASTM D5993 | g/m² | 4,000 min | 4,100 min |
| Mass of bentonite, oven-dry | ASTM D5993 | g/m² | 3,700 min | 3,700 min |
| Moisture content | ASTM D5993 | % | 35 max | 35 max |
| Tensile strength, MD | ASTM D6768 | kN/m | 4.0 min | 4.0 min |
| Peel strength | ASTM D6496 | N/m | 360 min | 360 min |
| Permeability · index flux | ASTM D5887 | m/s · m³/m²/s | 5 × 10⁻¹¹ · 1 × 10⁻⁸ max | n/a |
| Flux after 0.05 M CaCl₂ permeation, 35 kPa | ASTM D6766 | m³/m²/s | 1 × 10⁻⁷ max | n/a |
| Geotextile & yarns — strength retained, 60 °C × 50 d | GRI-GCL3 §5.6.2 (D5035) | % | 65 min | n/a |
| Geofilm — strength retained, 60 °C × 50 d | GRI-GCL3 §5.6.4 (D882) | % | n/a | 80 min |
Requirements per JG/T 193-2006 · Table 2 · by grade
GCL-NP needle-punched by nominal bentonite mass · GCL-OF (+ HDPE film) and GCL-AH (adhesive) to order · the standard the factory certificate is issued against
Swipe sideways for all grades →
| Property | Test method | Unit | 4000 | 4500 | 5000 | 5500 | 6000 | GCL-OF | GCL-AH |
|---|---|---|---|---|---|---|---|---|---|
| Mass per unit area, oven-dry | §5.4 · 105 °C | g/m² | ≥ 4,000 | ≥ 4,500 | ≥ 5,000 | ≥ 5,500 | ≥ 6,000 | ≥ 4,000 | ≥ 4,000 |
| Bentonite swell index | §5.5 · 2 g / 100 ml, 24 h | ml / 2 g | ≥ 24 | ||||||
| Methylene blue absorption | JC/T 593 | g / 100 g | ≥ 30 | ||||||
| Tensile strength | GB/T 15788 · 300 mm/min | N / 100 mm | ≥ 600 | ≥ 600 | ≥ 600 | ≥ 600 | ≥ 600 | ≥ 700 | ≥ 600 |
| Elongation at maximum load | GB/T 15788 | % | ≥ 10 | ≥ 10 | ≥ 10 | ≥ 10 | ≥ 10 | ≥ 10 | ≥ 8 |
| Peel, nonwoven to woven | GB/T 2791 · 300 mm/min | N / 100 mm | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 40 | ≥ 40 | – |
| Peel, PE film to nonwoven | GB/T 2791 · 300 mm/min | N / 100 mm | – | – | – | – | – | ≥ 30 | – |
| Permeability coefficient | Annex A (≡ ASTM D5084) | m/s | ≤ 5.0 × 10⁻¹¹ | ≤ 5.0 × 10⁻¹¹ | ≤ 5.0 × 10⁻¹¹ | ≤ 5.0 × 10⁻¹¹ | ≤ 5.0 × 10⁻¹¹ | ≤ 5.0 × 10⁻¹² | ≤ 1.0 × 10⁻¹² |
| Hydrostatic head, 1 h, no leakage | Annex B | MPa | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.6 | 0.6 |
| Fluid loss | JC/T 593 | ml | ≤ 18 | ||||||
| Bentonite durability | §5.13 · 168 h, 0.1 % CaCl₂ | ml / 2 g | ≥ 20 | ||||||
Required values of the two standards, not a mill test result. GRI-GCL3 (Rev. 5, 2019) sets one floor for bentonite mass — 3,700 g/m² dry; the 4,500 – 6,000 g/m² grades are heavier loadings bought against the same test regime. JG/T 193-2006 names the 4,000 / 4,500 / 5,000 / 5,500 series; 6,000 g/m² is made to the same requirements. We cut, dry and weigh the bentonite, run swell index and peel strength on your batch before the balance payment.
The Lining Decision
GCL, Membrane, Or Both?
GCL alone
The forgiving choice
Ponds, canals, reservoirs, secondary containment. Self-heals punctures, no field welding at all — panels just overlap with bentonite paste. The right answer where installation skill is the biggest risk on site.
Membrane alone
The dry choice
Where nothing may pass at all and the substrate is well prepared — evaporation ponds, biogas, aquaculture. Needs proper welding and QC, and it never forgives a missed hole. The membrane page
Composite: GCL + membrane
The regulator's choice
Landfill cells and anything with leachate: the membrane does the sealing, the GCL underneath catches whatever finds a defect. Most modern landfill specs simply require both. We ship them as one package.
The Heaviest Product In The Family
Freight Is Part Of The Spec Decision
Because GCL weighs out the container, ocean freight per m² runs several times higher than for membrane — and over-speccing the loading costs you twice: once at the mill, once on the water.
Every container, weight-capped
Whatever the loading, the box grosses out near the road limit. The m² you get for that fixed tonnage is the whole freight game.
One roll of 4,000 g GCL
Site logistics matter: a telehandler or spreader bar to place rolls, dry storage off the ground — bentonite that wets early swells early.
What you save on site
No welding crew, no seam testing, no welder in the container. Overlap, paste, backfill — the installation economics often pay back the freight.
Before It Ships
Three Numbers, Weighed And Tested On Your Batch
Loading: cut samples, dry them, weigh the bentonite — the label is a claim, the scale is a fact. Swell index: quality sodium bentonite swells ≥24 mL per 2 g; calcium-blended clay swells less and seals worse, and it's the classic substitution. Peel strength: the needle-punch bond that keeps the sandwich together on your slopes. We've run this exact battery on GCL shipments and send the lab sheets with photos before the balance payment.
Landfill tenders get the standards conversation up front — GB/T, ASTM D5993-family tests, whatever your engineer's checklist calls for — so the paperwork matches the product on the truck.
Straight Answers
GCL Sourcing FAQ
What bentonite loading do I need?
Ponds and canals typically run 3,000–4,000 g/m²; landfill bases and caps 4,500–5,000; heavy containment up to 6,000. Your engineer's permeability requirement decides it — and because freight is weight-capped, over-speccing costs twice. We quote the loading your duty needs, landed.
How is GCL installed — do I need welders?
No welding at all. Panels overlap 150–300 mm with bentonite paste or granules in the seam, then get covered. That's the quiet economic argument for GCL: the installation crew needs no specialist equipment, and there are no seams to test.
What's the swell index and why does it matter?
It measures how much the clay expands in water — quality sodium bentonite swells to 24 mL per 2 g or more. The classic substitution is calcium-blended bentonite: cheaper, swells less, seals worse. It looks identical dry, which is why we lab-test the swell index on the actual batch.
Why is GCL freight so expensive per square metre?
Because the container hits its ~27 t weight limit long before it's physically full — a 40'HQ carries only 5,000–9,000 m² depending on loading, versus ~29,000 m² of 1 mm membrane. The per-m² freight is therefore several times higher, which belongs in the buying decision from day one.
Can you ship GCL together with geomembrane?
Yes — composite lining packages (GCL + membrane + protection geotextile) are the standard modern landfill build, and we consolidate them into the same shipment with one document set. Weight planning across the mixed load is exactly the kind of maths we do before quoting.
Loading-Matched Quote
Grams In.
Lab Sheet Out.
Tell us the duty, the area and the loading your design calls for. We come back with the spec, the freight-aware landed price, and the test plan — usually within one business day.
Loading weighed on cut samples, not labels
Swell index & peel strength lab-tested per batch
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