The thickness and structure of an asphalt paving project ultimately depends on the anticipated use of the pavement once it is finished. For example a driveway will be structurally different than say a truck stop parking lot. But there’s more involved, as asphalt pavement involves an entire structure and few critical decision making points involving sub-grade materials, drainage and anticipated traffic.
Application of asphalt that is too thick will make it impractical to achieve compaction throughout the entire depth. This would result in premature breakdown or unraveling of the asphalt, wasted money on excess material, and tire marks from vehicles at rest. The result of applying too thin is the obvious premature breakdown and fracturing from vehicle traffic.
Below is a breakdown on how asphalt should be applied for specific scenarios:
Residential driveways typically use 2 to 3 inches of asphalt with 3" being suitable for occasional large trucks or heavy equipment. Three inches is the maximum thickness asphalt should be applied to ensure compaction.
Commercial parking lots with standard car/ truck traffic should be completed in two layers, each layer not exceeding 2 inches or less than 1 ½ inches. For heavy duty use such as semi truck traffic, asphalt should not be less than 2 inches per lift and no thicker than 3 inches thick per lift.
Underneath the asphalt you should have 5 to 8 inches of granular base aggregate depending on the type of soil. Underneath the granular base aggregate, you have soil. If your local soil is gravelly, rocky, or sandy it will provide good drainage and doesn’t move much with the seasons. Therefore, less gravel is required to achieve a stable base. But if your soil is loamy or clay it may need to be excavated and replaced to a certain depth, before it causes serious problems later. Soil that is loamy or clay holds water, and is technically impervious to water, so when you apply pressure to saturated clay, you force the water to displace causing everything above and around it to move. Depending on the type of anticipated traffic and drainage. It may be necessary to excavate up to 10 inches of subbase inorder to install 5-6 inches of 1.5 inch rock to create a bridge over the clay or loamy soil prior to the application of class 5.
Northern Pavement Maintenance offers high-quality asphalt and paving services for our communities surrounding the twin cities. As our area’s leading asphalt company, we pride ourselves on delivering excellent work at an affordable price, backed up by outstanding customer service. For commercial and residential paving and the maintenance of asphalt surfaces please contact us today at 763-784-6200!
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