Asphalt Paving Hints

Asphalt's makeup

• Asphalt is actually the shortened name for asphaltic cement concrete. It is a flexible paving material that has three basic components: an aggregate such as gravel, a fine aggregate such as sand, and a binder, which is asphalt cement. These materials are mixed in the proper proportion and then heated, which melts the binder. The mixture is then applied hot to the prepared surface.

Contractor considerations

• Asphalt paving is not a do-it-yourself job. It requires the skills of a licensed, bonded, insured and experienced excavation contractor and grading and paving contractor. Consult people you know who have had paving work done for recommendations, as well as local building contractors or landscapers who may work with reputable paving companies. Get a number of quotes from recommended contractors so as to get the best work at the best price. When talking to contractors, mention any special considerations that pertain to your job such as the size of the project, the slope or grading of the site, or anything that might need to be worked around such as curbs or stairs. If something needs to be removed and reinstalled, such as a gate or pipes, make sure the contractor's quote includes that work as well.

Cost

• Asphalt is a petroleum-based product and as such is subject to cost changes that correlate to the rise and fall in oil prices. There is also some price fluctuation based on demand at a particular time in a particular area. Building Journal.com has a useful online construction asphalt driveway calculator that helps you figure the approximate job cost of paving a driveway in more than 160 United States cities.

Site preparation

• Asphalt can be laid over existing asphalt. If, however, you are replacing concrete with asphalt, the existing concrete must be broken up and removed. It is helpful to know that used concrete can be sold for use in other construction projects.

  If you are laying asphalt on a previously unpaved surface, the surface must be properly prepared to accept it. This involves preparing the subgrade soil and laying down base materials before applying the asphalt. The underlying soil must be made stable, which will likely involve some combination of removal and replacement of unsuitable soil and vegetation, compaction and moisture control. Base materials, usually compacted gravel or crushed stone, are laid on top of the sub-grade soil, usually to a depth of six to 10 inches. Proper drainage of the surface is also important and is achieved by creating a "crown" or slightly higher center that slopes to the edges.

Weather considerations

• Asphalt paving should only be done in dry weather and at a minimum temperature of 45 degrees Fahrenheit. Be sure when hiring a contractor that he is not under such a tight schedule that he is forced to work on your project when weather conditions are not ideal. If you live in an area with changeable weather, this can result in long lead times, so take that into consideration when planning your project.

Laying the asphalt

• The layers, or courses, or asphalt concrete are applied on top of the base material. Usually there are two courses. These are called the binder course and the wearing course. The binder (base) course has a lower asphalt content and a coarser aggregate than the wearing (surface) course. Over the wearing course a sealant is then applied to prevent water intrusion. Asphalt cures as it cools and is typically ready to take traffic in 24 to 48 hours.