What Is It Made Of: Asphalt

A common question we receive is regarding the differences between asphalt, poured concrete, stamped concrete and concrete pavers (interlock). There are many myths about how each performs and the maintenance required to keep them in good shape.

In this article (part one of four), we’ll generalize over the properties of asphalt, how to install asphalt and the maintenance required for asphalt pavement.

Asphalt

I would venture to say that asphalt is the most commonly used paving product in the world. You name the function, driveways, city streets, highways, parking lots, it’s being used somewhere on the planet.

With the lowest production cost compared to other paving solutions, asphalt remains the go-to for infrastructure. Now don’t be fooled, there are also significant differences in construction between the way a city street, highway or private residential driveways are installed.

How It’s Made

Asphalt is a combination of aggregates (various stone sizes & sand) and asphalt glue (5% of the total mix). The glue is strong and almost elastic-like. This binds the aggregates together to create a pliable and water impermeable service.

Asphalt is mixed at a plant in hoppers where the plant will either use 100 percent new materials or will include as much as 40 percent recycled asphalt road or asphalt shingles. These materials are mixed and heated before being dumped into a dump truck and taken to its new home.

Installation

Before being installed, preparations will take place for the base. The area will need to be excavated and proper base material will be brought in and compacted. Depending on where you live, the climate will dictate how thick this base will need to be.

Once the base is compacted, the asphalt mix can be dumped, hand raked, and machine raked into place. In the final stage, the asphalt will be compacted with either walk behind plate compactors, ride on roller and hand tampers to tackle the tight areas and sides.

Depending on your climate, and to the quality you want the asphalt, will determine how thick the pavement will be. In general, a very good asphalt driveway will be between 3″-5″ inches when compacted.

Maintenance

Maintenance will prevent the need to prematurely redo the pavement. This will save thousands of dollars over the long term and is something to consider.

Crack Sealing: Sealing cracks is crucial to ensuring that no water penetrates the surface. Water damage can quickly destroy the surface and result in potholes, large cracks, chipping and heaving from freeze-thaw.

Seal Coating: Recommend every 3 to 5 years, seal coating is crucial to preventing oxidization from the sun, water runoff and general wear and tear from traffic. There are some ideas that seal coating should be completed every 1 to 2 years, but this can lead to cracking.

Edging: Creating a sharp edge between asphalt and lawns will prevent grass or other plants from growing into the edges which could lead to cracking or accelerated deterioration.

Oil Spots: Although not directly an issue to be overly concerned about, they will be visually unpleasant. Over time these oil spots can become softer and could lead to premature deterioration. Best to clean oil spots as it occurs.

Fuel Spills: Regular unleaded gasoline like oil will not damage the asphalt. It would take time if at all to lead to premature deterioration. However, diesel fuel is another matter entirely. If left uncleaned, diesel fuel will dissolve the binders in the asphalt mix. A pothole may take form as the asphalt can flake or chip away.

Anti-icing & De-icing Products: Asphalt is virtually immune to the harmful effects of anti-icing and de-icing products. However, if the condition of the asphalt already had many untreated cracks, salt can play a more significant role in the freeze/thaw action. Typically these products will leave residue and a good cleaning come Spring is ideal.

Learn More

Would you like to learn more about the in’s and outs of asphalt paving? Check out a valuable resource at All About Driveways.com.