Two suppliers can both quote a “composite geomembrane” while picturing different rolls. One may mean a membrane bonded to geotextile on one side; another may mean textile on both sides. If the inquiry gives only a total mass or a product name, those quotations are difficult to compare.
Start with the project drawing. Show the layer sequence, the material and requirement for each layer, and which properties apply to the finished composite. VABREN can then review the requested construction and tests against the order requirements.
Confirm what each layer must do
The polymer membrane is the low-permeability barrier. The bonded textile may be specified for protection, handling or another function identified by the project designer. Describe whether the textile is required on one side or both, what it will contact in the installed system, and whether it must meet a separate filtration or mechanical requirement.
Do not assume that a composite roll can replace a separately installed HDPE geomembrane and geotextile in every design. The two systems can differ in component properties, joint detailing, installation sequence and how each layer is tested. The project engineer should approve any substitution.
Write the component requirements separately
For the membrane, provide the polymer, nominal thickness, tolerance and barrier performance required by the contract. For each textile layer, state its material, construction, mass per unit area and any required strength, puncture or hydraulic properties. Identify which properties apply to the individual components and which apply to the bonded composite.
Illustrative mass check: If a drawing calls for a 1.0 mm HDPE membrane between two geotextiles of 200 g/m² each, and the membrane density is assumed to be 0.94 g/cm³, the simple component calculation is about 940 + 200 + 200 = 1,340 g/m². This is only an example for checking whether an RFQ describes each layer. Actual finished-roll mass and acceptance tolerances depend on the approved materials and production method; they must be confirmed by measurement, not inferred from this calculation. The 0.94 g/cm³ assumption matches the lower bound for formulated sheet density in GRI GM13, a specification for standalone HDPE geomembranes, not for the full composite.
Also specify the finished roll width and length, the required bonding arrangement and the method planned for field joints. The joint detail may depend on how the textile is opened or treated at the seam; it should be agreed before production and installation, not improvised after the rolls reach the site.
Check the standard and test plan
List the exact standard and edition named by the project. China’s current GB/T 17642-2025 covers geocomposites made of nonwoven textile and geomembrane; it may be relevant when the ordered structure falls within its scope and the contract calls for it. An international project may use other standards and test methods. Standards with different scopes should not be treated as automatically equivalent.
Request a test plan that identifies the sample, method, acceptance value and report format for each required property. Ask how rolls and batches will be identified on the shipping documents so the delivered material can be matched to its test records.
Composite geomembrane RFQ checklist
| Item | Questions to answer |
|---|---|
| Application | What is the lining system, substrate, cover and expected service condition? |
| Layer structure | Is textile required on one face or both? Which face contacts each adjoining layer? |
| Membrane | What polymer, thickness, tolerance and barrier properties are specified? |
| Textile | What material, construction, mass and mechanical or hydraulic properties are specified? |
| Finished roll | What bonding, width, length, handling and packaging conditions are required? |
| Site joints | What joint method and installation documents does the approved design require? |
| Inspection | Which standards, test methods, values and batch records must be provided? |
From drawing to confirmed order
Send the latest drawing with the inquiry and mark any properties still open for discussion. Ask each supplier to quote the same layer structure and test requirements. Once the details are agreed, record the roll construction, tests, packing, quantity and delivery schedule in the purchase documents.
Review VABREN’s composite geomembrane page, then send your layer diagram and required parameters for an order-specific review.