Breaking It Down: Installing a Segmental Pavement Driveway

By Jim Carlson, Pave Tech Consultant

Once all field pavers are laid, we used a marking tool to outline the soldier course. With the edge restraint pre-installed, it glides along the vertical wall to precisely mark each paver needing to be cut. Once cutting is complete, the soldier course shows no unsightly gaps.

Running a marathon takes thousands of steps, but crossing the finish line remains the goal. Hardscape construction is similar. Because there is no substitute for years of jobsite experience, this article is only a starting point for further education.

Before the ‘real’ work starts, you need the job. Companies live and die by taking their hard hats off, and throwing their sales hats on. When you bring up the word bid, money just might be the first thing that comes to mind. But even in these lowly economic times, price should never be the reason a job is accepted or rejected. Beyond business factors such as overhead costs and profit margins, selling yourself continues to drive work to those with more than just a low bid.

The frosted tempered glass lens of the paver lights used diffuses the LED light while withstanding loads up to 7 tons when installed. These stainless steel, maintenance free lights weigh almost as much as actual pavers. All images courtesy Pave Tech.

Following the site visit, you need to contact the utility companies for locating and marking all areas in the excavation area. Never assume the location of existing utilities. Now is the time to order materials including base material, bedding sand, pavers, edge restraints, fabric, and any other required materials. Proper material placement on the jobsite will help reduce wasted labor.

When excavating to proper sub grade depth also extend the excavation beyond the edge of future pavement. The rule of thumb is that base extension should be equal to the depth of the base. If the project calls for an 8” compacted base, the excavation area must extend 8” from edge of pavement where edge restraints will be used. This displaces the load on the pavement to a larger surface area and allows spikes to be driven into compacted base rather than soil. Accurate sub grade elevations allow uniform layering of the aggregate base. Finished excavation elevations should be within 1/4” of the designed plan. Always fill over excavated areas with base; never add extracted soil. Every mistake can increase material, equipment, and labor costs. The site visit determined that the natural grade did not require adjusting. Once excavation has been completed, you are ready to build your base to its proper elevation.

The woven fabric was placed directly on top of the soil subgrade, starting at the lowest elevation. Each layer is ‘shingled’ with an 18” minimum overlap. Make sure that the fabric runs up the sides and out of the excavated area to prevent any base migration and maintain strength. The fabric can be cut back with a knife or a propane torch after installation.

A base rake’s dual edge head moves loose material with the flat side and cuts down high spots with the rake side. Standard garden rakes separate the fine and large aggregate, preventing proper base compaction.

The 13,500 lb centrifugal force Weber CR7 compactor (at right), maximized efficiency by compacting up to 6-8” of loose material at once (with proper moisture content). The machine digitally signaled when optimum compaction had been achieved.

Made of PVC, Pave Edge has the ability to move under load, yet return to its original form. Although partly due to its material, the patented design makes a major difference. The triangular, reinforced hollow core design ensures the vertical wall stays perpendicular to the pavement, while allowing truly straight edges and gradual curves.

A woven geotextile was used to separate the clay subgrade and base. By greatly reducing the clay’s ability to push into the compacted base material, the strength of the base remains intact for years.

With the base completed, the project takes shape by installing the edge restraint. Equally important as proper base and durable pavers, the edge restraint holds the entire pavement together. Many believe the type of project you are working on (i.e. walkway, patio, driveway, etc) determines which edge restraint should be used. Engineering tests performed by Stork Twin City Testing Corporation, found residential pavements typically receive their greatest horizontal loads during compaction. The edge restraint’s responsibility is to withstand horizontal loads created by traffic.

Running a marathon takes thousands of steps, but crossing the finish line remains the goal. Hardscape construction is similar because many don’t realize the number of steps involved in completing an entire hardscape project. But by looking at those steps from start to finish, we can begin to appreciate what crossing the finish line takes.

Pave Edge was specified for this project. The frost heave/sand retention lip is designed to be placed under the paver and sand. This prevents sand migration from under the pavers and reinforces stability from load, moisture and any annual freeze thaw cycles. If sand were to migrate, as it can with edge restraints without lips, the loss of bedding sand will result in joint sand loss. Loss of joint sand will result in loss of pavement interlock, which is a major benefit over other types of pavements.

Using coarse concrete sand for the bedding sand allowed for proper drainage without the potential rutting that mason sand can produce. For many projects, using the same sand for the bedding and joint sand is both economical and convenient. Following sand screeding, a parallel reference line to the garage was snapped. Then a perpendicular reference line was snapped. We began laying pavers where these two lines meet at the lowest possible grade to eliminate shifting pavers. By building the pavement up and evenly on both sides of the perpendicular line (pyramid method), the bond lines are kept straight. Before setting the soldier course, low voltage wire was laid on top of the bedding sand for architectural paver lights that were installed after installation was complete.

The site visit determined that the natural grade did not require adjusting. A 2 percent minimum grade away from structures should be maintained to allow for proper water flow. The most common method to control water run-off is the ‘Sheeting’ method. This offers a flat pavement surface, while allowing the necessary grade for proper drainage.

After adjusting bond lines, the pavement was initially compacted without joint sand, forcing bedding sand up into the joints. Coarse, dry concrete sand was then swept over the surface before making several more passes with the plate compactor. Continue compacting until the joints are completely filled. The coarse sand may take more passes with the compactor to thoroughly fill the joints, but offers superior interlock over fine joint sand.

As you can see, there’s a lot more to installing interlocking pavers than a 10 minute YouTube video might suggest. As our industry continues to grow, my hope is that new contractors and customers alike understand what really goes into a properly installed segmental pavement.