Geomembrane Liners
rLLDPE Exposed Membrane - Floating Covers & Exposed Lining
Scrim-reinforced LLDPE membrane in FC45 (1.14 mm) and FC60 (1.52 mm), black/black or black/tan. For floating covers, exposed roof lining and permanently exposed containment where UV, biaxial stress and spanning loads govern. NSF/ANSI 61 certified for potable water contact.
Overview
An exposed membrane has a different job from a buried liner. It carries continuous biaxial stress, wind uplift, rainfall ponding and unshaded UV, and on a floating cover it must also rise and fall with the liquid beneath it through every operating cycle. Standard HDPE is too rigid for that duty and unreinforced LLDPE is insufficiently reinforced for the spanning loads. Scrim-reinforced LLDPE - a 9 × 9 weft-inserted 1,000 denier polyester scrim fully encapsulated between two layers of UV-stabilised LLDPE - is engineered for exactly these conditions.
Two grades are supplied. FC45 at 1.14 mm carries a 20-year outdoor service life; FC60 at 1.52 mm carries 30 years. Both are available in black/black or black/tan, are NSF/ANSI 61 certified for potable water contact, and weld with standard LLDPE extrusion and hot-air equipment - no specialist plant or consumables, which matters on remote African sites where mobilising unusual equipment is the constraint.
The black/tan option is not cosmetic. A tan upper face reflects rather than absorbs, lowering surface temperature and thermal cycling on permanently exposed installations, which is the mechanism behind much long-term degradation of exposed membrane in high-insolation climates.
Applications fall into three groups. Floating covers on TSF water recovery ponds, potable water reservoirs, effluent dams and biogas digesters, where evaporation suppression, algae control, odour containment or gas capture is the objective. Exposed roof and tank lining, where the membrane is the weatherproofing element. And general exposed containment - process water dams, attenuation ponds, bunds and lined channels - where cover soil is impractical and the liner must survive unshaded.
Floating cover work is a design scope before it is a supply scope. Panel layout must resolve liquid level variation, wind uplift, rainwater drainage geometry, access hatch positions and anchor detail before a seam is made. Geosynthetics Africa has installed floating cover systems across Southern and West Africa and executes every scope under IAGI-aligned QA/QC - one of only five IAGI Installer Members on the continent - with panel layout design, certified installation, vacuum-box and air-channel seam testing to ASTM D5641, destructive sampling to ASTM D6392, and a signed QA dossier on handover.
- MaterialScrim-reinforced LLDPE · 9 × 9, 1,000 denier PET scrim
- StructureScrim encapsulated between two UV-stabilised LLDPE layers · 1.14 mm and 1.52 mm
- ColourBlack/Tan (BT) · Black/Black (BB) on request
- StandardGRI GM25 · NSF/ANSI 61
- Roll WidthCustom widths · factory-fabricated panels to project layout
- Roll LengthMill rolls and factory-fabricated accordion-folded panels
Typical Properties
| Property | Test Method | FC45 | FC60 |
|---|---|---|---|
| Thickness (typical) | ASTM D5199 | 1.14 mm | 1.52 mm |
| Weight | ASTM D751 | 1,040 g/m² | 1,069 g/m² |
| Tongue tear strength | ASTM D5884 | 601 N | 600 N |
| Grab tensile at break | ASTM D7004 | 1,557 N | 1,602 N |
| Puncture resistance | ASTM D4833 | 556 N | 600 N |
| Outdoor service life | - | 20 years | 30 years |
| Potable water | NSF/ANSI 61 | Certified | Certified |
| Standard | GRI GM25 | GM25 | GM25 Cat. 1 |
| Colours | - | Black, Tan | Black, Tan |
Note: The above specifications represent the product family properties. Please refer to the product datasheet for individual SKU values.
Typical Applications
View all applicationsPond & Reservoir Lining
FC60BT floating covers for potable water reservoirs - NSF/ANSI 61 certified for direct drinking water contact. Prevents contamination, algae growth and UV degradation of stored water.
Containment & Lining
Floating covers on TSF water recovery ponds to contain tailings liquor and suppress evaporation. Also used on process water dams and heap leach pond covers across African mining operations.
Floating Covers for Water Storage
FC45 and FC60 scrim-reinforced LLDPE floating covers for TSF water recovery ponds, potable water reservoirs, effluent ponds, biogas digesters and evaporation suppression - the primary application for reinforced LLDPE geomembrane.
Compatible Systems
View all systemsBlack - FC45BB / FC60BB
Both faces black - the standard production colour. Carbon black content provides the primary UV protection mechanism, absorbing UV radiation and preventing photodegradation of the LLDPE resin. Black is the default specification for all floating cover applications and carries the full published mechanical and outdoor life ratings. Available in FC45BB (1.14mm, 20-year) and FC60BB (1.52mm, 30-year)
Black/Tan - FC45BT / FC60BT
Black underside, tan top face. The tan upper surface has lower solar absorptivity than black, reducing surface temperature under direct sun exposure - relevant in high-irradiance African environments where minimising thermal expansion and heat stress on the cover is a design consideration. Tan is also specified where visual identification of the cover surface is important for maintenance access, or where a lighter appearance is preferred for potable water reservoirs. Both black/black and black/tan carry identical scrim construction, mechanical specifications and NSF/ANSI 61 certification. Available in FC45BT (1.14mm, 20-year) and FC60BT (1.52mm, 30-year).
Installation Guidance
Standard Method Statement
Floating cover installation begins with design. Before any material is cut or seamed, Geosynthetics Africa produces a detailed cover layout drawing accounting for pond geometry, operating liquid level range, maximum and minimum freeboard, wind uplift loads, rainwater drainage design, access hatch positions, and anchor perimeter detail. The installation method - dry or wet - is determined at design stage based on the structure type and liquid level conditions at time of installation.
Two installation methods are used depending on site conditions. Dry installation is carried out in an empty or dewatered structure - the cover is fabricated and laid directly over the base, with foam floats and ballast tubes positioned per the layout drawing. As the structure is filled, the cover rises with the liquid level, taking up its designed floating geometry. Wet installation is used where the structure is in service or cannot be emptied - the cover is fabricated adjacent to the structure and progressively pulled across the liquid surface as additional panels are seamed. Both methods are executed by Geosynthetics Africa using the same QA/QC standards and deliver the same outcome: a fully floating, anchored and tested cover system
Cover deployment is carried out with the pond at or near operating liquid level to allow the cover to float into position under controlled conditions. Panels are deployed sequentially from one end of the pond, weighted temporarily to prevent wind uplift, and progressively seamed as deployment proceeds. The cover perimeter is anchored to the pond wall or anchor trench using the specified detail - ballast tubes, concrete anchor beams or perimeter batten systems depending on the All field seams are made using extrusion or hot-air welding with compatible LLDPE welding rod. Trial welds are produced and tested before production seaming begins. Completed seams are non-destructively tested - vacuum-box (ASTM D5641) or air-channel pressure test - and destructive peel/shear samples taken per the project QA plan to ASTM D6392. The completed cover system includes closed-cell foam floats for buoyancy, sand tube ballast lines to control drainage geometry, rainwater sump and pump or gravity drainage, and access hatches at specified locations. All penetrations, vents and anchor details are installed and sealed as part of the Geosynthetics Africa scope.
On completion, Geosynthetics Africa delivers a full QA dossier: seam log, NDT test results, destructive test records, panel as-built drawing, penetration and anchor detail records, rainwater system commissioning record, and a signed handover certificate. A cover maintenance guide covering inspection frequency, repair procedures and rainwater pump maintenance is included with every handover package.
Quality Assurance & Testing
Field QA/QC Checklist
- Material Conformance: Roll numbers and manufacturer QC certificates checked against GRI-GM13 (HDPE) or GRI-GM17 (LLDPE); conformance samples taken where the CQA plan requires.
- Trial Welds: Trial seams made and peel/shear tested at the start of each shift, for each welder and machine, and whenever conditions change.
- Non-Destructive Seam Testing: 100% of seams tested: air-pressure testing of double-wedge welds (ASTM D5820) and vacuum-box testing of extrusion welds, patches and repairs (ASTM D5641).
- Destructive Seam Testing: Seam samples cut at intervals set by the CQA plan (GRI-GM14) and tested in shear and peel to ASTM D6392 against GRI-GM19 values.
- Cover System Check: Ballast, float and sump layout, rainwater removal and perimeter anchorage installed to the approved cover design.
- Potable Water Approval: Where the cover is in contact with drinking water, material approval for potable water use confirmed before installation.
Manufacturing Standards
- GRI-GM13 / GRI-GM17 material specification
- GRI-GM19 seam strength requirements
- ASTM D6392 seam strength testing
- ASTM D5820 / ASTM D5641 non-destructive testing
- Potable water approval (where applicable)
- GRI GM25 · NSF/ANSI 61
Documents
Product Selection Guide
Compare performance properties across the entire category hierarchy before specifying.
Installation & Method Statement
Standard deployment procedures, installation specifications, and field application method statements.
QA/QC Site Checklist
Field quality control procedures, inspection checklists, and testing standards to verify installation integrity.
Technical Data Sheet (TDS)
Guaranteed minimum average roll values (MARV) and material testing properties.
Chemical Resistance / Accessories Guide
Chemical compatibility matrix and list of auxiliary materials needed for installation.
Projects Using rLLDPE Exposed Membrane - Floating Covers & Exposed Lining
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