If you know what to expect in the installation of your deck or patio, then you might be able to prevent mishaps or misunderstandings from occurring. Below is a brief, step-by-step process of the installation of interlocking concrete pavers. This process can be applied toward most paving applications.
Layout and excavation of a site
The layout of an interlocking concrete pavement is where the drawing is translated into reality. In addition to knowing the size of the project and excavated area, the layout forces the contractor to consider the sequence of job functions and crew involvement. Considering all factors in advance helps ensure a smooth operation.
Preparing the soil subgrade
As with the 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 consume up to 70 percent of the labor. For example, if the job will be completed in five days, you can expect the soil subgrade and base to be prepared in three days. Preparing the subgrade is setting the table for the rest of the pavement. Attention must be given to understanding the type of soil, and the amount of compaction.
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 increases the weight per unit volume (or density) of soil. When a soil is compacted, the air spaces between the voids decrease. Compaction achieves four main purposes: it will increase the soil’s load bearing strength; prevent pavement settlement/rutting; reduce seasonal movement and help ensure that any movement is uniform.
Installing Geotextiles (optional)
Geotextiles 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 the 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, a minimum 4 inches of thickness is recommended. For residential driveways over well-drained soils, a minimum of 6 inches of thickness is recommended. These thicknesses will be increased in colder climates or over continually wet or weak soils. Most driveways in freezing climates are at least 10 inches thick.
Installation of edge restraints
Edge restraints are a critical component of all interlocking concrete pavements. They hold the pavers in place for the life of the pavement.
Sand is installed over the base to a consistent thickness. ICPI guidelines note that bedding sand can be installed between ¾ inches and 1½ inches thick. With the compacted base and uncompacted bedding sand installed to these tolerances, the pavers are ready for installation.
Choosing the right paver for the job
It is important to choose the right pavers for the application. As a rule of thumb, pedestrian areas and residential driveways will achieve interlock with 2 3/8-inch-thick pavers. Another important consideration is the size of the paver. It is important that you ask your contractor whether the pavers they are using are the recommended size for the application.
All jobs with concrete pavers will involve cutting. There are three basic tools for cutting pavers: the mechanical splitter, the powered table saw and the hand-held gas powered quick saw. Professional contractors should take care to control the dust from cutting pavers but you should always expect that there will be dust during this process. Cutting pavers is also noisy.
Compacting the pavers in place
Pavers are first compacted without joint sand to create initial interlock. All pavers should have two passes of the plate compactor over them prior to filling the joints with joint sand. After this is complete, dry joint sand is spread and swept and the pavers compacted again until the joints are completely full. At the end of the day all pavers should be compacted in place within 6 to 8 feet of any unfinished edge.
Below is a list of information you should be aware of regarding paver installation.
Make sure the excavated area will be a minimum of six inches wider than the actual paved area. The extra width will help ensure stability of the base at the edges, and provide space for the required edge restraints.
For proper draining, the slope from the paved area will be at a minimum of 2 percent.
If compacted properly, the aggregate base will not absorb or hold water and its density will minimize deformation and/or heaving of the paved surface during freezing or thawing.
An aggregate base, which is composed of crushed rock or sand, will be compacted in 4-inch layers to achieve the maximum density and load bearing capacity. Each layer will require several passes of a compactor to achieve this. The loosely placed, even layer of washed, coarse sand provides a setting bed for the pavers. Its depth will be no thicker than one and one-half inches thick. When the pavers are placed on the sand and compacted, the sand moves up into the joints. This causes the pavers to interlock and become level after compaction. Note: limestone screenings and stone dust should not be used for bedding sand.
If you have a chance to watch the installation process, make sure the pavers are taken from multiple bundles or pallets simultaneously to ensure an even mixture of color.
An edge restraint will be installed around the perimeter of the pavers to eliminate horizontal creeping of the pavers and loss of bedding sand.
Sealant is not necessary, however, it may enhance the colors and may prevent staining. Allow a minimum of 60-90 days after completion of the installation before sealing. Consult your supplier for recommendations on cleaning and sealing.