Using Geogrid to Reinforce a Retaining Wall

If your project involves stabilizing slopes or retaining earth, you will need geogrid. Geogrid is a synthetic, flexible mesh designed for these purposes, available in various materials, strengths, and sizes. Made from woven polyester or high-tensile strength plastic, it comes in rolls and is available in both uniaxial and biaxial forms. Biaxial geogrid, most commonly used for retaining walls under 10 feet, can be rolled in both directions while maintaining its reinforcement properties, unlike uniaxial geogrid, which can only be rolled out in one direction.

How Does Geogrid Work?

To understand Geogrid’s effectiveness, perform a simple test. Take two cylinders, one with compacted material and the other with compacted material plus a mesh representing geogrid. Apply vertical force to both and observe how the soil reacts.

Installing Geogrid with AB Aztec or AB Europa Walls

• Foundation and First Layer: Start with the foundation. Use either AB Aztec or AB Europa blocks, placing the edge of the geogrid against the back of the raised front edge and rolling it out along the wall. For AB Fieldstone, place the geogrid edge in the middle of the facing unit. Refer to your plans for exact locations and sizes.
• Placing Blocks: Arrange the blocks so their seams are offset by at least 1/4 of the block length. Align the retaining wall properly, making necessary adjustments for a straight line.
• Tensioning Geogrid: Pull the back of the geogrid to remove slack and, if needed, stake it in place. Avoid compacting or driving on the geogrid to prevent damage.

Compacting and Backfilling

• Wall Rock Installation: Fill the block cores and 12 inches (300mm) behind the block with wall rock. Use approved on-site soils or infill to backfill behind the wall rock to the height of the block.
• Compacting: Compact in lifts of 8 inches (200mm) or less, starting on the blocks and moving parallel to the block towards the excavation area. Make at least two passes with a plate compactor. The compacted soil should be solid and stable. Clear excess material from the top surfaces of the blocks, ensuring they are clean and smooth.
• Continuing Construction: Install the next level of blocks and geogrid as per the plan, repeating the steps to the desired height. Finally, fill behind the blocks with organic soil or approved on-site soil to prevent water from running behind the blocks and to support plantings above the retaining wall.

Installing Geogrid with AB Fieldstone Walls

• Foundation and Geogrid Placement: After installing the foundation, roll out the geogrid from the center of the AB Fieldstone facing back to the excavated area. Stack the next set of blocks (facing/anchoring unit) so the vertical seams are offset by at least 3 inches (75mm) or ¼ the block length.
• Tensioning and Staking: Remove slack from the geogrid and stake it before installing wall rock and infill soil. Avoid running compaction equipment on the geogrid.

Creating Patterned Retaining Walls

• Design and Installation: Patterned walls offer a unique look, blending different block sizes to create a hand-laid stone appearance. You can use preset patterns or design your own. For curved or reinforced walls, use a two-procedure pattern.
• Craftsmanship and Detail: Creating a hand-laid wall look requires craftsmanship and attention to detail. Allow extra time, especially if it’s your first attempt. Use either the AB Europa or AB Collection for preset or irregular patterns, refer to the Pattern Chart for details. Ensure a level surface on the reinforced wall for irregular patterns to properly install the geogrid.

Biaxial Geogrid: Applications and Benefits

Biaxial geogrids are crucial for creating stable landscapes that resist erosion. They are composite or plastic lattice structures used to reinforce roads, retaining walls, and slopes. Providing stability in both latitudinal and longitudinal directions, biaxial geogrids are durable and made from punched or extruded polymers, preventing soil erosion effectively.

Geogrid Properties

Geogrids have several properties that make them useful for construction:

• Tensile Strength: Resistance to breaking under tension.
• Radial Stiffness: Load distribution in all directions.
• Confinement: Prevents granular material like soil from shifting.

By locking soil particles in place, geogrids create long-lasting, erosion-resistant soil structures, reducing maintenance needs.

Common Applications

Geogrids are widely used in:

• Road Construction: Increasing roadway lifespan by strengthening the subgrade and evenly distributing vehicle weight.
• Retaining Walls: Reinforcing soil behind walls to reduce pressure and prevent failure.
• Slope and Soil Stabilization: Allowing steeper slope construction by stabilizing layers of soil with geogrid.

Biaxial geogrids, with their ability to lock soils and add strength in multiple directions, are invaluable for construction projects. Ensure your projects stand the test of time by incorporating biaxial geogrid.