Geogrid for retaining wall, across all face systems.

Reinforced soil vs gravity / cantilever.

Retaining walls come in two structural families.

• Gravity and cantilever walls. Mass concrete, reinforced concrete cantilever, semi-gravity. The wall carries the retained earth pressure through its own mass and structural rigidity. No geogrid inside the retained fill. Suited to short walls (less than about 2 m) and to projects where the face must be a structural concrete element (urban architectural wall, basement retention, headwall).
• Reinforced soil walls. Segmental block (SRW), MSE precast concrete panel, gabion-faced reinforced wall, modular small-block residential. The wall gets its stability from horizontal layers of geogrid inside the compacted granular backfill, connecting back into the retained mass. The face is dressing. Geogrid is essential. Suited to medium-to-tall walls (2-10+ m), to projects where modular fast-build is preferred, and to projects with available back-of-face space (typically 0.7-1.0 times wall height).

For wall-system selection across the broader family see our retaining wall comparison page. This page focuses on the geogrid spec within reinforced-soil wall family.

Four face systems, four connection details.

StrataGrid PET grades mapped to wall design.

The geogrid grade selection comes out of the BS 8006 / FHWA design rather than from a wall-height rule of thumb; but indicative ranges for typical Malaysian wall geometries help with first-pass quoting.

For very tall walls (above 10 m) or unusual loadings, layered combinations of two geogrid grades through the wall height optimise the cost; we run the layered design as part of the quote.

The two design checks that govern wall geometry.

Pullout capacity

The pullout check confirms that the geogrid can develop sufficient tensile resistance beyond the active wedge (the portion of backfill that would slide if the wall failed). Pullout capacity is expressed as a force per metre of geogrid width per metre of embedment length, calculated from geogrid aperture, backfill friction angle, and overburden pressure at the geogrid horizon. Per BS 8006 Annex A and FHWA-NHI-10-024:

• Embedment length beyond active wedge must be at least 1.0 m at every layer.
• Total reinforcement length normally 0.7-1.0 times wall height for routine walls; can extend longer (1.0-1.5 H) for tall walls or weak backfill.
• Pullout factor of safety typically 1.5 per BS 8006; 1.5-2.0 for critical structures.

Pullout often governs design for the lower / shorter geogrid layers and for the upper part of tall walls. The standard fix is increasing embedment length (longer layers are often cheaper than higher-grade geogrid at the same horizon). Our geogrid pullout calculator handles first-pass sizing.

Connection capacity

The connection check confirms that the geogrid-to-face connection (block, panel, gabion mesh) can transfer the design tensile from geogrid into face system without failure of the connection itself. For SRW the connection capacity is the NCMA-tested block-plus-geogrid combination value; for MSE panel it is the panel-system-tested capacity at the panel anchor; for gabion it is the mesh-and-rock-fill capacity at the wrap; for modular small block it is the friction value (typically 70-90 percent of geogrid tensile).

For most face systems and routine grades, connection is not the governing design check; but for tall walls with high horizon tensile and for block systems with low intrinsic connection capacity, connection can govern and limit the geogrid grade usable at that face system.

Two reinforcement tiers working together.

For taller walls (above about 4 m) and for walls with tight face-stability requirements, the geogrid layout normally combines two tiers.

• Primary reinforcement. Full-length geogrid (0.7-1.0 H length, anchored beyond active wedge) at design vertical spacing (typically 0.3-0.6 m). Carries the global wall tensile per BS 8006 / FHWA internal-stability design.
• Secondary reinforcement. Short-length geogrid (typically 1.0-1.5 m, behind face only) at intermediate vertical spacing (typically 0.15-0.30 m, halfway between primaries). Provides face-connection redundancy, controls face bulging between primary layers, and improves face compaction by confining the back-of-face fill. Secondary is usually a lower-grade product than primary (sometimes a biaxial PP rather than uniaxial PET).

The primary-plus-secondary layout costs marginally more in geogrid but significantly improves face performance and reduces the visual and structural penalty of any local irregularity in fill placement. Standard for SRW above 5 m and for any MSE wall above 4 m.

From foundation to capping.

1. Foundation preparation. Excavate to design foundation level, place 100-150 mm of compacted granular bedding, check level. For soft foundation, supplement with basal mat per basal reinforcement page.
2. First course of face. Lay first course of block (SRW), set first row of panels (MSE), or place first course of gabion baskets. Level and align.
3. First lift of backfill. Place 200-300 mm of granular backfill (specification typically: angular crushed stone or quarry waste, well graded, max 75 mm, fines less than 10 percent, friction angle minimum 30 degrees). Compact to 95 percent MDD in 150-200 mm layers.
4. First geogrid layer. Roll out StrataGrid uniaxial PET across the lift, machine direction perpendicular to wall face. Length per design (0.7-1.0 H typical). Connect to face per face-system detail. Tension by walking back from face to anchor end.
5. Cover with next backfill lift. 0.3-0.6 m of granular backfill above the first geogrid; compact.
6. Next face course. Lay next block / panel / gabion course; check alignment, batter, set-back.
7. Continue lift / geogrid / face cycle to design wall height. Standard build rate 0.5-1.5 vertical metres per crew per day depending on face system and access.
8. Capping and drainage. Cap course (SRW, MSE), top-of-wall drainage, surface profile. Permanent drainage (back-of-wall filter, weep pipes, outlet) connected to site drainage. See geotextile for drainage for the back-of-wall filter.
9. QA documentation. Layer compaction record, geogrid delivery certificate per layer, connection check record per face course, face line / batter survey at completion.

Combined wall scope.