Reinforced Retaining Walls

Retaining wall
construction
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Working with Geogrid

Install grid

Install geogrid in the machine or roll direction


Reinforcement Grid

Reinforcement Grid


Geogrid typically comes in large rolls up to 13 ft (4 m) wide and 250 ft (76 m) in length. These “grids” also come in a variety of weights and strengths. Taller walls often require heavier strength grids, especially in the bottom portions of the wall. More information on types of geogrid.


It is critical that the correct grid is installed in the retaining wall. Check the engineered plans and specifications.


Most grids are strongest along the roll or machine direction. Reinforced grid designs require that all grids are placed with the machine direction running from the face of the wall towards the back of the excavation area.

See more information on using grid with corners and curves.

See the importance of reinforcement in your retaining wall with this sand castle demonstration.

How Grid Works

The sand castle test takes two cylinders of soil and applies vertical force to see how the soil performs. The first cylinder is just compacted material. The second is also compacted material with the addition of mesh screens to simulate the use of geogrid reinforcement. Learn more about how grid works...

Step 1: Site Prep and Excavation

Foundation soils at the bottom of the base trench must be firm and solid. If the soils are made up of heavy clay or wet soils, or the areas have been previously excavated, remove entire material and replace with granular base, compacting in 8 in. (200 mm) lifts or less.



reinforced retaining wall base course cross section

Reinforced retaining wall base course cross section



retaining wall installation

Install base material, level, and compact.


Install retaining wall base course

Install retaining wall base course


retaining wall installation wall rock

Install base course and wall rock


Compact wall rock and backfill soils

Compact wall rock and backfill soils


Step 2: Install Base Material

The base material can be any compactible granular material. Allan Block recommends a well-graded aggregate, with a balanced mix of grain sizes, ranging from 0.25 in. to 1.5 in. (6 mm to 38 mm) diameter.

Step 3: Install Base Course

Step 4: Install Wall Rock and Backfill Material

Step 5: Compact

Compaction of the material behind the block is critical for a quality retaining wall.


retaining wall geogrid installation

Install geogrid and stake into place


retaining wall installation compaction

compact in 8in. (200 mm) lifts


retaining wall installation compaction

Keep heavy equipment away from the back of the block


retaining wall installation compaction

Install additional courses


Step 6: Install Geogrid

Refer to the plans for placement of grid; this example starts on the base course.

Step 7: Backfill and Compact

Step 8: Install Additional Courses

Install facing unit

Install AB Fieldstone facing units. Level and Adjust


Install anchoring unit

Install AB Fieldstone anchoring units


retianing wall installation Remove All Excess Wall Rock Material

Sweep to remove excess materials for proper placement of the next course


Compact wall rock and backfill soils

Compact wall rock and backfill soils


Roll out geogrid behind the retaining wall

Install geogrid. Start in the middle of the facing unit and extend behind wall.


retaining wall installation stack next course

Stake geogrid in place. Install next course of block


retaining wall installation compaction

From the second course and up, compact starting on the wall and working to the back of the reinforced zone


Step 1: Install Base Course for AB Fieldstone

Step 2: Install Wall Rock and Backfill Materials

Step 3: Compact

Compaction of the material behind the block is critical for a quality wall

Step 4: Install Geogrid

Step 5: Backfill & Compact

Step 6: Install Additional Courses


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