If you are building a multi-meter reinforced soil retaining wall (MSE), a steep slope, or a bridge abutment that supports the backfill thrust for decades, uniaxial geogrid is the structural component that prevents collapse due to accumulated creep under sustained load. This MOLTEXO PP uniaxial geogrid delivers 80 kN/m of directional strength with low creep, in a 3 m x 100 m roll, a calibrated dimension for typical highway and urban development MSE walls.
The installation of a uniaxial geogrid is NOT comparable to that of a biaxial geogrid: the procedure requires prior structural engineering design (not optional), strict control of the roll orientation (the strong axis must be perpendicular to the wall face) and a precise layer-by-layer laying sequence with compaction between each layer. This guide covers the operational procedure on site, NOT the structural dimensioning—the calculation of wall height, layer spacing, and geogrid length per layer must always come from the responsible designer.
Product specifications
The polypropylene uniaxial geogrid is offered in a single standard presentation of 3 m wide by 100 m long, with an auditable directional strength of 80 kN/m along the roll. The following table includes the complete technical specifications of the only available variant:
| Specification | Value |
|---|---|
| SKU | 654761 |
| Material | Mono-oriented stretched polypropylene (PP) |
| Orientation type | Uniaxial (stretched in one direction) |
| Tensile strength | 80 kN/m (5.5 kip/ft) along the roll |
| Creep resistance | Low, calibrated for long-lasting MSE walls |
| Roll width | 3 m (9.8 ft) |
| Roll length | 100 m (328 ft) |
| Area per roll | 300 m² (3229 ft²) |
| Chemical resistance | Inert to acids, alkalis, and soil microorganisms |
| Estimated service life | Decades in buried conditions |
| Main application | MSE walls, reinforced slopes, abutments |
| Color | Black (with anti-UV carbon black additive) |
The sister guides for PP biaxial geogrid and PP triaxial geogrid cover the other two orientations of the family, specifically designed for horizontal reinforcement of road bases and subgrades—structural work different from MSE walls.
Step-by-step usage guide
The following procedure covers the operational cycle on site: from structural design verification to layered backfill with compaction. Supervision by a qualified structural or resident engineer is always mandatory for MSE walls and retaining structures; the following indications are operational guidelines and do not replace the specific engineering design for each project.
Structural design verification and layout
Before any field work, confirm with the project engineer: the height of the wall or slope, the vertical separation between geogrid layers, the horizontal length of each geogrid layer (which defines the "embedment" in the backfill), and the type of granular or cohesive backfill approved. Without this prior design, installation is blind construction and compromises structural safety. Lay out the wall base and verify the foundation's level.
Foundation preparation and first layer
Excavate to foundation level according to design. Compact the bottom to the specified minimum density. Place the first layer of granular backfill and compact. Mark on the backfill the line where the visible face of the wall will be placed (concrete blocks, gabions, formwork soil bags, as indicated by the project). The first geogrid roll is extended over this layer.
Roll laying with correct orientation
Unroll the geogrid so that the LONGITUDINAL DIRECTION OF THE ROLL IS PERPENDICULAR TO THE WALL FACE. This is critical: the 80 kN/m strength is only in the longitudinal axis of the roll. If you lay the roll parallel to the face, the geogrid will be in its weak axis, and the wall will progressively collapse. Visually mark the direction of the roll on site (e.g., with paint on the ground) to avoid operator errors in subsequent layers.
Anchoring at the face and overlap between rolls
The roll must extend to the wall face (blocks or facing system) and "wrap" the front as indicated in the project details. At the face, the geogrid is anchored by the weight of the upper backfill and by specific mechanisms of the facing system. If you need several rolls in the same layer to cover the wall length, transversely overlap (parallel to the face) a minimum of 50 cm—but NEVER overlap longitudinally (perpendicular to the face) as this cuts the strong axis of the geogrid. If the roll length is insufficient to cover the wall length, individual cuts with vertical displacement of the joint between layers are necessary.
In tall MSE walls where the geogrid is laid in many layers, mark each roll on site with the layer number before spreading (with paint, construction tape). Visual control of which layer corresponds to which prevents orientation errors and allows the resident engineer to audit progress without daily plan review. Once covered by backfill, there is no way to inspect the position of the lower layers: traceability must be built during execution.
Layered backfill and compaction
Place the next layer of granular backfill over the spread geogrid. Dump the material from the inside towards the outside of the wall (NEVER from front to back, as this would push the geogrid and compromise its anchoring at the face). Compact each layer to the specified Proctor percentage before spreading the next geogrid layer. The vertical separation between geogrid layers comes from the design—typically between 30 cm and 60 cm depending on the total wall height.
Do not install uniaxial geogrid with the roll direction parallel to the wall face. This is the most expensive and common mistake in inexperienced works: the geogrid is stressed along its weak axis (typically between 5 and 10 kN/m of transverse strength instead of the 80 kN/m of the strong axis), and the wall progressively deforms over months or years until collapse. On-site detection is visual: look at the geogrid nodes; the long "fluid" pattern in the direction of the roll is the strong axis and must be perpendicular to the wall face.
Need to verify the design before ordering quantities?
Calculating the correct quantity of uniaxial geogrid for an MSE wall depends on interdependent variables: wall height, horizontal length of each layer (which is a function of the calculated thrust), vertical spacing, and length of each face. Errors in estimation can lead to costly shortages that halt work or overages. Ask the virtual assistant with your project data, and we will guide you on order calculation based on the structural design.
Complementary Products
To complement uniaxial geogrid in MSE walls, slopes, and retaining structures, the following products cover the most common adjacent needs:
Biaxial PP geogrid is the specific solution for horizontal reinforcement of road bases and industrial platforms: different structural work, not an alternative to uniaxial but a complement in integral projects. Woven PP geotextile is used in MSE walls as a separation layer between the granular fill and the natural soil, preventing contamination by fines in drainage systems. Metal rods are useful as temporary anchors during spreading and visual verification of correct orientation before backfilling. Triaxial PP geogrid is a solution for different problems (soft subgrades with complex traffic) and does not replace uniaxial in MSE walls.
Maintenance and Care
Uniaxial geogrid buried in MSE walls does not require maintenance during its service life. What does require monitoring is the wall's behavior: in structural walls (especially those of significant height), it is advisable to establish a program of periodic visual inspection of the outer face to detect signs of progressive deformation, localized bulging, cracks in block joints, or differential settlement at the top. These signs can indicate that something is not right internally, long before collapse. Visual inspection every 6 months during the first 5 years of life is good practice.
For storage prior to installation, keep the rolls horizontally, on a clean surface, covered against direct sunlight. Uniaxial geogrid is more susceptible to mechanical damage at the edges than biaxial: a blow against a stone during unloading can initiate a tear that propagates when unrolling. Visually inspect each roll before lowering it to the site and before spreading it, especially the first and last meters that may have been exposed during transport.
Frequently Asked Questions (FAQ)
Why can't I use uniaxial where the project calls for biaxial?
Uniaxial geogrid has very low strength in the transverse axis (perpendicular to the roll), typically between 5 and 10 kN/m. If used in a road base where vehicular loads come from any direction, the weak axis is stressed and the geogrid does not provide reinforcement in part of the plan. Uniaxial is optimized for situations where the tensile force is in a single known direction (perpendicular to a wall face). For bidirectional subgrade reinforcement use biaxial; for multidirectional with complex traffic, triaxial.
What do I do if the roll length is not enough to cover the wall from end to end?
The horizontal length of each layer comes from the structural design (typically between 0.7 and 1.0 times the wall height). If the wall length exceeds the 100 meters of the roll, several sections per layer are necessary with a transverse overlap of at least 50 cm (parallel to the face). NEVER overlap longitudinally because that cuts the strong axis. To coordinate the joints between layers, displace each layer at least 1 meter from the previous one to avoid continuous weak planes.
Can I use uniaxial geogrid to reinforce an existing slope at risk of sliding?
Yes, it is one of the typical uses. Installation involves excavation, laying geogrid layers with compacted fill, and reconstructing the slope with a more stable geometry. This intervention ALWAYS requires prior geotechnical engineering design to evaluate potential failure planes, existing soil properties, and surcharge. Correct geogrid installation on a problematic slope can prevent a landslide; incorrect installation can accelerate it by giving the user a false sense of security.