1: Prepare the base leveling pad.
After selecting the location and
length of the wall, excavate the base trench to the designed width
and depth. Compact the base trench soils prior to placing any stone
or concrete in the trench. Start the leveling pad at the lowest
elevation of the wall. Level the prepared base with a minimum of six
inches of well-compacted granular fill or concrete. Keystone
recommends additional trench depth for below grade placement of
Keystone units on a ratio of one inch below grade for each eight
inches of wall height above grade (to a maximum of three units
buried.) This lowers the base course below grade locking the wall in
place and also helps prevent erosion and scouring at the base of the
wall. The base trench should be wide enough to allow for the unit
and drainage zone. Walls built to a level condition on a sloping
grade require a stepped base. It is best to work out the stepped
base as the wall steps up in elevation.
Step 2: Install the
When installing the first course, be
sure the paired pinholes face up. Place units end-to-end with
corners/edges touching and be sure each unit is level—side to side
and front to back. Use a string line across the back edge of the
units to ensure that the wall is straight. This base course is
critical for accurate and acceptable results.
Step 3: Insert the interlocking
Place two pins in each unit. With the
Pinned System, it is easy to build a near vertical wall or a
set-back wall. For a near-vertical design, place pins in front
holes. Use the rear holes for 1 - 1 1/4-inch set-back. When
constructing curved walls, use the front pin position for best
results. This will minimize any gapping or binding on curves.
Step 4: Install and
Fill in all voids—in and between
Keystone units—using 3/4 inch (20mm) aggregate. Place drain zones
and 4” perforated pipe behind the units if required to achieve a
minimum two foot depth of drainage zone from unit face. Compact
material in unit cavities appropriately to eliminate settling. When
clay or poor soils are present we recommend that the entire geo-grid
zone be backfilled with sand, clean angular crushed stone, quarry
dust or other suitable granular material.
Step 5: Install additional
IInstall additional courses starting
at the straight wall areas. Place units so that they are centered
over the two pins below and centered over joint. When stacking the
units, pull them toward the face of the wall until it makes full
contact with both pins.
Step 6: Install Keystone caps.
the wall with caps by applying or all weather efflorescence-free non
shrink premixed mortar adhesive for concrete (such as Nutech
Maxipoint) on the top surface of the last course before applying cap