The following overview will help you understand the installation basics of a good interlocking concrete pavement system.
Site layout and excavation
The layout of interlocking concrete pavement is where the drawing is translated into reality. In addition to knowing the size of the interlocking concrete pavement and excavated area, the layout tells the contractor the sequence of job functions and crew involvement. Considering all factors in advance such as material storage and paving direction helps ensure a smooth operation.
Preparing the soil subgrade
As with layout and excavation, proper preparation of the pavement foundation is one of the most important elements of the job. Soil subgrade and base preparation should involve up to 70% of the labor. This time should result in a well prepared soil subgrade and base.
A properly prepared soil subgrade will support the base above it and allow the base to perform its role of distributing the loads and stresses from above. The soil type should have been identified before starting the job, during the bid proposal. It can affect the estimate on labor hours and the type of equipment required for the job.
Once the soil type is identified, the contractor will need to compact it. Compaction achieves four main purposes: it increases the soil’s load-bearing strength; prevents pavement settlement/rutting; reduces seasonal movement; helps ensure that any movement is uniform. When compacted properly, the aggregate base density will minimize deformation and/or heaving of the paved surface during freezing or thawing.
For proper drainage, the contractor will slope the paved area away from the house at a minimum of 2%.
Geotextiles (special fabrics) are recommended over clays or silts. They are also a good choice over soils saturated for a large portion of the year. The fabric separates fines in soils from the base and prevents them from migrating upward into the base.
ICPI recommends minimum base thickness for different applications. For pedestrian areas, including patios and walkways, for example, a minimum 4 in. (100 mm) thickness is recommended. Your contractor should know the technical requirements for base thickness that apply to your particular installation.
Edge restraints around the perimeter of the pavers are essential for eliminating horizontal creeping of the pavers and loss of bedding sand. They hold the pavers in place for the life of the pavement.
Sand is installed over the base to a consistent thickness—between ¾ inch (20 mm) and 1½ inch (40 mm) according to ICPI guidelines.
Proper paver types and sizes
It is important to choose the right pavers for the application. As a rule of thumb, for example, pedestrian areas and residential driveways will achieve interlock with 2 3/8 inch (60 mm) thick
pavers. (Ask your contractor whether the pavers they are using are the recommended size for the application.) The contractor will assure an even color mix by taking pavers from several bundles or pallets at a time.
All jobs with concrete pavers will involve cutting. Professional contractors should take care to control the dust from cutting pavers, but you should expect that there will be dust—and noise—during this process.
Paver compaction and Joint Sand
Pavers are first compacted without joint sand to create initial interlock. After this is complete, dry joint sand is spread and swept and the pavers compacted again until the joints are completely full. Following compaction, you and the contractor should inspect the pavement together to ensure satisfaction.
Paver sealing (optional)
While pavers are extremely durable, sealing may enhance the colors and can prevent staining. Allow a minimum of 60-90 days after completion of the installation before sealing. Consult your supplier/contractor for recommendations on cleaning and sealing.