The Smart Start Small
For those new to bituminous-set paving, there are additional variables that simply don’t exist for traditional sand-set paver installations. Knowing these variables and planning accordingly is essential for a successful and profitable installation. “There’s a lot more work to it, but the benefits make it worth the trouble, especially for commercial applications,” says Mike LaMonica, estimator and project manager for Syrstone.
Bituminous-set applications on a rigid concrete base have a proven track record of superior performance under heavy vehicular traffic, especially in urban settings, according to ICPI’s Tech Spec 20: “Construction of Bituminous-Sand Set Interlocking Concrete Pavement.” Though more expensive (typically 30-50% higher than sand-set pavers due to additional materials and labor), long-term performance justifies the cost when compared to sand-set installations under the same wheel loads. Interlocking concrete pavement crosswalks with bituminous setting beds on concrete bases have an estimated lifespan of 7.5 million 18,000 lb equivalent single axle loads or ESALs, according to ICPI’s Tech Spec 19.
Bituminous setting beds on a rigid base have replaced mortar or sand-cement bedding materials in many pedestrian applications and in nearly all vehicular ones. Mortar-set pavers have not performed well under vehicular traffic and are susceptible to deterioration from freeze-thaw and exposure to deicing salts. Concrete bases are recommended in vehicular and pedestrian areas; asphalt bases should only be used in pedestrian areas.
MANAGING THE VARIABLES
There are two main variables with bituminous-set paver jobs that require upfront research and planning before putting a bid together. The first is availability of materials. Where is the nearest reputable asphalt batch plant that can produce a smaller quantity of the mix needed (7% asphalt to 93% concrete sand)? The plant will likely have a regional DOT-spec top mix or a performance-grade mix that is similar to ICPI guide specifications. Once a plant is located, the distance to the jobsite needs to be considered for determining trucking costs. For vehicular traffic installations, is traffic already present at the site that will require partial access? If so, the installation may need to be completed in phases which will require separate truckloads. Be sure to build the additional trucking costs of multiple deliveries into the estimate, as well as the minimum delivery load and the anticipated spoilage if the minimum is in excess of the needed quantity. These costs can add up and eat into profit margins quickly if not considered from the outset.
The second main variable is timing. “Everything with the bituminous setting bed is time-dependent,” Mr. LaMonica explains. The concrete or asphalt base is placed first and must cure. Next, an emulsified asphalt tack coat may be needed (recommended for vehicular applications, but typically not required for pedestrian applications) that will require curing time. Then, the bituminous setting bed is laid and must cure. On top of that, a neoprene-asphalt (neo-asphalt) adhesive must be applied that also requires curing. Planning around these downtimes is critical to efficiently manage labor hours. Ideally during curing downtimes, crews can work on cutting pavers or on another part of the installation that may be sand-set, or on housekeeping tasks to keep the jobsite clean and orderly. Typically, commercial jobs involve multiple other trades so keeping feet off of the installation-in-progress can be a challenge, but is very important given the messy nature of the materials. Vigilance is required and good communication will help prevent other crews from making a mess, especially if they are not familiar with the process and stages during which the surface should not receive foot traffic.
For those looking to enter the world of commercial projects by taking on a bituminous-set installation, Mr. LaMonica advises to start small, do your research and have the proper funds.
“I almost envy the residential installer who has the design eye to incorporate multiple hardscape components into his work,” Mr. LaMonica says. “The contractor has more control in the residential world because he can see the job through from beginning to end.”
The commercial world is so different, Mr. LaMonica says. A construction manager oversees the whole project, the paperwork and record keeping are a distraction, the profit margins are generally lower, payment is slower and design changes are often problematic to get approved and paid. “I tell the residential guy looking to do commercial, if you can’t afford to fund a job for 60, 90, or 120 days, you shouldn’t be in that world,” Mr. LaMonica says.
ICPI’s Commercial Paver Technician Installer Course covers bituminous-set paver installation. For more information, visit http://www.icpi.org/installerdesignations.