Resources
Technical datasheets, installation guides and reference material to help your team specify and install Willem Olaf geosynthetics with confidence.
Technical Datasheets
Download full specifications for each product range. Enter your details once and we'll email you the link.
Geomembranes Datasheet
Tensile strength, thickness, roll dimensions and test methods for our Geomembranes range.
Geotextiles Datasheet
Tensile strength, thickness, roll dimensions and test methods for our Geotextiles range.
Geogrids Datasheet
Tensile strength, thickness, roll dimensions and test methods for our Geogrids range.
Geocomposites & Drainage Datasheet
Tensile strength, thickness, roll dimensions and test methods for our Geocomposites & Drainage range.
Installation Guides
Step-by-step guidance for site teams installing Willem Olaf products.
Geomembrane Welding & Installation Guide
Subgrade preparation, panel deployment, wedge and extrusion welding, and seam testing for HDPE and LLDPE liners.
Geotextile & Geogrid Placement Guide
Roll orientation, overlap widths, anchorage and compaction guidance for separation, filtration and reinforcement layers.
Geocomposite & GCL Installation Guide
Handling, overlap and hydration guidance for drainage geocomposites, geonets and geosynthetic clay liners.
Frequently Asked Questions
A geomembrane is an impermeable sheet — typically HDPE or LLDPE — used to contain liquids or gas, such as in a reservoir or landfill liner. A geotextile is a permeable fabric, woven or non-woven, used to separate, filter, drain or reinforce soil layers. The two are often used together, for example a non-woven geotextile cushion beneath a geomembrane liner.
For weak or lateritic subgrades, a woven geotextile separation layer combined with a biaxial or triaxial geogrid is the standard solution — the geotextile prevents fines from pumping into the sub-base, and the geogrid distributes wheel loads. Our technical team can recommend the specific grade based on your CBR values and traffic loading.
Yes. Our range is manufactured and tested to ISO 9001, ASTM (D6693, D4833, D4595 and related test methods), EN (13361, 13251, 13249) and DIN 16726 standards. Test certificates are available on request and can be supplied for tender submissions.
Yes — wedge and extrusion welding are both field-proven in West African conditions. High ambient temperatures generally aid welding, though seams should be tested by air-channel or vacuum-box methods regardless of weather, and welding should be scheduled to avoid the hottest part of the day to maintain consistent seam quality.
Standard product lines held in our Lagos warehouse are typically available for delivery within 2-5 working days to most Nigerian states. Non-stock items or large project quantities may require a longer lead time — confirm availability when you request your quote.
Yes. Small product samples are available on request so your team can verify material thickness, texture and weight before specifying a product for your project.
Roll widths and lengths vary by product — see the Available Specifications table on each product page. Most rolls can be supplied at standard factory dimensions; custom panel sizes for geomembranes can be factory-fabricated for some grades on request.
Design life depends on the product and application. Covered HDPE geomembranes are typically rated for up to 50 years, and buried geogrids for up to 100 years, provided the product is correctly specified, installed and protected from prolonged direct UV exposure.
Our technical team can provide on-site guidance during installation for larger projects, and our installation guides (available in this Resources section) cover placement, overlap and welding procedures for self-installing contractors.
Yes — datasheets are available for download from this page, and full test certificates and compliance documentation can be issued on request to support tender and procurement requirements for government and private-sector projects.
There's no fixed minimum for stock items — we supply quantities from single rolls up to full project volumes. For non-stock or imported grades, a minimum order quantity may apply; this will be confirmed with your quote.
Store rolls on a flat, dry surface, raised off the ground, and keep them wrapped in their factory packaging until installation to protect against UV exposure, moisture and contamination. Avoid stacking heavy items on top of rolls.
Yes. We regularly supply projects across Nigeria and the wider West African region. Delivery timelines and freight costs to your site will be confirmed as part of your quote.
We work with the procurement and documentation requirements typical of federal and state agency projects, including pro-forma invoices, tax documentation and phased delivery against project milestones. Speak to our team about the specific terms for your contract.
Glossary of Geosynthetics Terms
Common terms used across our datasheets and product specifications.
- Apparent Opening Size (AOS)
- The effective pore size of a geotextile, used to assess how well it retains soil particles while allowing water to pass.
- CBR Puncture Resistance
- A test method (based on the California Bearing Ratio plunger) that measures a geotextile's resistance to puncture by sharp aggregate or stones.
- Design Life
- The period over which a geosynthetic product is expected to perform its intended function, based on material formulation, installation conditions and exposure.
- Dimple Sheet
- A moulded HDPE sheet with a studded or "dimpled" profile that creates a drainage void, commonly used in basement and retaining wall drainage.
- Extrusion Welding
- A site welding method for geomembranes in which molten polymer extrudate is applied along a seam, used for detail work, repairs and patches.
- Geocomposite
- A manufactured material combining two or more geosynthetic functions — for example a drainage core bonded to a geotextile filter — in a single product.
- Geogrid
- A polymer grid structure with regular apertures that interlocks with surrounding soil or aggregate to distribute load and reinforce weak ground.
- Geomembrane
- A flexible, impermeable synthetic sheet — typically HDPE or LLDPE — used to line ponds, canals, landfills and containment structures.
- Geonet
- A net-like drainage core, usually extruded HDPE, that provides a high-flow channel for liquid or gas, often laminated with geotextile to form a drainage geocomposite.
- Geosynthetic Clay Liner (GCL)
- A thin factory-manufactured liner consisting of a layer of sodium bentonite clay bonded between geotextile carriers, providing a low-permeability barrier in place of a thick compacted clay layer.
- Geotextile
- A permeable fabric — woven from polypropylene yarns or needle-punched into a non-woven sheet — used for separation, filtration, drainage or reinforcement within soil.
- HDPE (High-Density Polyethylene)
- A dense, chemically resistant polymer used to manufacture geomembranes and geogrids, valued for its strength, durability and resistance to a wide range of chemicals.
- Leachate
- Liquid that has percolated through solid waste in a landfill, picking up dissolved and suspended contaminants, which must be contained and collected by the lining system.
- LLDPE (Linear Low-Density Polyethylene)
- A flexible polyethylene resin used for geomembranes that need to accommodate ground movement or differential settlement, such as flexible pond and tank liners.
- Permittivity
- A measure of the rate at which water flows through a geotextile in the direction perpendicular to its plane — a key property for filtration applications.
- Subgrade
- The natural or prepared ground surface beneath a road, foundation or lining system, onto which sub-base, fill or geosynthetic layers are placed.
- Sub-base
- A layer of compacted granular material placed above the subgrade and below the road base or surface course, often reinforced or separated using geosynthetics.
- Tensile Strength
- The maximum load per unit width a geosynthetic can withstand before failure when stretched, a key property for reinforcement applications.
- Transmissivity
- A measure of the rate at which a liquid flows within the plane of a geosynthetic drainage layer, used to design drainage cores and geocomposites.
- UV Stabilisation
- The addition of carbon black or other additives to a polymer formulation to protect against degradation from prolonged exposure to ultraviolet sunlight.
- Wedge Welding
- A site welding method for geomembranes in which a heated metal wedge fuses two overlapping sheets together to form a continuous double-track seam, allowing the seam to be air-tested.
Ready to specify? Get a free technical consultation.
Send us your project details and our technical team will respond within 24 hours.