Have you ever wondered why all those layers to a road? Why cant you not put asphalt down on the ground and go? The simple answer is the asphalt alone is not strong enough to support the weight of vehicles.

Why is an aggregate base important?

There are two main purposes of an aggregate base. One is to offer a foundation to allow larger loads to travel on the pavement. The other is to give a frost barrier to prevent heaving when the temperatures drop. You need the base to avoid paying more in repairs than you did building it.

What is used to make an aggregate base?

Aggregate bases are comprised of crushed rocks that are 20 millimeters or smaller. It can also be from recycled materials, such as concrete, from earlier construction projects. No need to worry, nobody is harmed in the making of the base.

How much of the base is necessary?

Well, that question takes a bit more of an intricate answer. The amount of base you need is heavily dependent on the subgrade or subsoil that is being used. In case you are wondering what those are, a subgrade is a densely compacted soil that has been reinforced with lime, concrete or other modifiers. The subsoil is a layer of soil in which the subgrade is placed.

A stable subgrade that has been reinforced or native soil that is gravelly in texture requires 2 to 4 inches of sub-base. If you are working with a subsoil that is at subgrade elevation, stable and free of organic matter then 8 to 10 inches of the base is necessary. All the same, if you have soft subsoil there may be the need for more remediation before laying the base to ensure proper stability.

Compaction is one of the most important parts of the process. Base materials need a mechanical source to allow proper compaction. Vibratory rollers are commonly preferred over static drum rollers as they cause vibrations that all compaction from the bottom up. Road constructors recommend using a vibratory roller wherever possible and to use a vibratory plate compactor in the areas the roller cannot reach.

Your asphalt company should know the base materials should not exceed 6 inches in all layers to allow good compaction. Should a layer exceed 6 inches the base should be installed in lifts. Remember, when using thick layers of base, 6 inches or more, extra time for settlement may be necessary.

Now you can see why an aggregate base is so important. Save yourself the time, trouble and money. Install an aggregate base before you lay the asphalt pavement. Call Roccie’s Asphalt Paving at (888) 88ROCCIES or (888-887-6224).