How to: The Compacted Base

Step 1 - Excavation

When we arrive to start a project, we always come prepared with dig locates to ensure there is no damage to underground infrastructure.
On a typical driveway base, we dig to a depth of 18"-20".
Residential walkways will see an excavation depth of 12"-14"
We always over dig the excavation area to allow for an interlock edge restraint.

Step 2 - Sub-Base Compaction

Once excavation is complete, we lower our plate compactor into the excavation area and begin compacting the subsoil below the interlock base.
This is done to solidify the sub-base for the entire interlock footprint.

Step 3 - Geo-fabric

Once the sub-base has been compacted, we install a layer of greenline woven geo-fabric.
This fabric wraps up all edges of the excavation area and has a minimum overlap of 12".
This fabric prevents the compacted base from migration into the sub-base.

STEP 4 - COMPACTION LAYERS

After the geo-fabric has been installed, we can begin the compaction stages.
This is the part of the compacted base which takes the longest. The compaction of the base is done in what we call "lifts". Each lift is done in increments of 3"-4".
Once granular A or 3/4" clear stone is brought into the excavation area, we add water (if applicable) and begin compacting.
This step is repeated until the base is within 4" of out final interlock height.

STEP 4 - CONTINUED

This is what a compacted lift looks like in the compacted base.

STEP 5 - DRIVE-GRID

Half way through the compacted base stage, we add a layer of Drive-Grid; an engineered mesh system which acts as a dimensional load distributor.
We use Drive-Grid to help mechanically stabilize the base, reducing potential settling and rutting.
In certain applications, two or three layers of Drive-Grid can be installed.

STEP 6 - SETTING PIPES & The BEDDING LAYER

Once our compacted base lifts have reached a few inches below interlock height, we set our grades and elevations using a system of heavy duty pipes.
Once set, compaction takes place between the pipes, and they are then doubled checked for accuracy.
After a final inspection of the grades/elevations, we install a min. 1" layer of washed concrete sand or 1/4" clear stone.
We strive on only using those two products for our bedding layer as limestone screenings (commonly known as 'Stone Dust') does not comply with ICPI Installation Standards.

STEP 7 - INTERLOCK INSTALLATION & POLYMERIC SAND

Once the bedding layer has been set, the pipes are removed from the compacted base & the area in which they were located is filled.
Interlock installation can begin. Using a system of string lines, we ensure that everything is nicely square.
Cuts are made (where applicable) and a plastic edge restraint is installed on the outer edges into the overbase.
We then move to the installation of the polymeric sand using a soft broom and a rolling compactor.
After ensuring there is no residual polymeric sand left on the interlock, we add water, activating the bonding agent.

STEP 8 - Sit back, RELAX & ENJOY!

Thank you for taking the time to learn about what goes into your interlock project. Both owners Denis Cashman and Raymond Logie have proudly passed the ICPI course, and continue to attend annual industry seminars in the Ottawa area to learn about the newest and best industry practices.