One of the greatest challenges associated with the long-term viability of asphalt pavement, is maintaining the structural integrity of the foundation. This is true for roads, parking lots, and even driveways. That’s why keeping moisture away from the underlying structure is key. Saturation and the incorrect handling of accumulated moisture will wreak havoc when they aren’t mitigated. This is where the potential for porous asphalt pavement construction can be deployed.
In its simplest form, porous asphalt pavement is a pavement method that contains high voids between the aggregates in the asphalt, allowing water to filter through the pavement into an underlying drainage base, and then into the water table. It’s intended to keep water moving away from the asphalt structure, increasing runoff, and saving on repairs. However, there are a few things to keep in mind when using this product.
Placement of porous asphalt pavement needs the right soil conditions to be optimally effective. That means that installation should only be done in areas with a permeable soil structure, which combats stagnation and constant “dampness” in the soil. If this characteristic is missing in the immediate soil underneath, microbiological decomposition of pollutants may be impeded.
Traffic Volume Considerations
Porous asphalt pavement can be used in many ways, which includes roads, but traffic volume does have to be considered. For lightly trafficked roads, parking lots, bike paths, and walkways, it’s ideal. But, for highways there are challenges with the variability of soil conditions, utilities, fills, and slope. Areas prone to heavy equipment and tractor trailers can also be problematic. The weight and sharp turns that are likely in those environments, means increased damage and clogging of porous pavement.
Construction Stage Placement
For sites that are being developed with porous asphalt pavement, the installation of the pavement should be scheduled as late in the construction cycle as possible. Due mainly to the concern for the clogging of the surface or the filling of the voids in the stone reservoir, late installation means reduced risk. When that’s not possible, having controls in place to handle storm runoff is critical.
Heavy Equipment Routing
Even if the asphalt placement is scheduled for a late stage, the subgrade at the installation site also needs to be protected. Excessive heavy equipment running in that area compacts the subgrade, severely impacting the permeability of the soil. Using equipment with oversized tires or ripping the subgrade after it’s been overly compacted can help address the issue.
A commitment to porous asphalt pavement installation means a commitment to its maintenance, long term. Vacuuming and power washing, a combined 2-4 per year, done in the spring and fall, should be part of the protocol. During the winter, deicing material can still be used, although at a smaller dosage than impervious pavements. However, sand and cinders shouldn’t be used because of the clogging factor.
It’s clear that porous asphalt pavement can be an ideal option. Taking into consideration the tips we’ve outlined, we’re confident of its effectiveness and longevity. At Four Corners Materials, we have a deep understanding of porous asphalt pavement construction. If you’ve got questions about maintenance or an upcoming installation, or if you’re ready to quote a project using the product, we’d be thrilled to help. Just contact us via our contact page or request a quote online and we’ll reach out soon.