GEOGRID INSTALLATION

For taller or more critical walls that require use of geogrid, continue the installation process with Step 5. If geogrid is not required, skip to Step 6.

Step 5A. Excavate Reinforced Soil Area.
Remove existing soils in the reinforced soil area to the maximum embedment length of the geogrid design. Provide a generally level soil condition behind the wall units for the placement of each geogrid layer.

Step 5B. Cut Geogrid.
Cut sections from geogrid roll to the specified length (embedment depth). Geogrid roll direction is from the wall toward the embankment. Check manufacturer's criteria for biaxial or uniaxial geogrids. In most cases correct orientation is to roll the geogrid perpendicular to the wall face.

Step 5C. Install Geogrid.
Hook geogrid over the Keystone fiberglass pins to ensure a positive mechanical connection between the unit and geogrid.

Step 5D. Secure Geogrid.
Pull the pinned geogrid taut to eliminate loose folds. Stake or secure the back edge of geogrid before and during backfill and compaction. Remove stakes, if desired, once backfill is placed. Place additional sections of geogrid, abutting each other, for continuous coverage at each layer.

Step 5E. Install Next Course of Keystone Units.

Step 5F. Place Compacted Backfill Over Geogrid In 8" Lifts.
Provide a minimum of 6" (150 mm) reinforced fill coverage prior to driving equipment over the geogrid with tired equipment. Avoid driving or turning vehicles directly on geogrid to avoid excessive damage.

Step 6. Install Additional Course.
Place the next course of Keystone units over the fiberglass pins, fitting the pins into the kidney-shaped recesses. Center the unit over the two underlying units as shown. Visually sight down in the kidney-shaped recess for pin positioning. Pull the Keystone unit toward the face of the wall until it makes full contact with both pins. For each remaining course, repeat Steps 3-6.

Step 7. Install Keystone Caps.
Complete your wall with Keystone Caps (see options on page 2). In areas of high public usage, apply Keystone KapSeal™ (a construction adhesive for masonry units) on the top surface of the last course before applying cap units. Place the Keystone Cap unit over the pins on the underlying unit. Pull the cap unit forward to the automatic setback position. Backfill and compact soils behind wall to finish grade. Finish grade with appropriate plastic soil cap or drainage swale to minimize surface water flow into wall/soil structure.