Written by Demetrius Sewell and published on https://www.ehow.com/
Asphalt driveways should be poured over a base of crushed stone, which is placed either on undisturbed grade, or on fill soil that has been mechanically compacted. When driveways sink, it’s most often because the underlying dirt was not properly compacted, or because the fill dirt contains debris (such as tree stumps) that are decomposing and collapsing underground. Asphalt driveway sinking can occur to varying degrees and for many different reasons. Initially, the problem will be isolated to a specific part of your driveway. However, if it’s neglected for too long, routine wear and tear can cause it to get worse and spread until your entire driveway becomes a liability.
How to Fix a Sinking Spot in an Asphalt Driveway
A common problem for homeowners with asphalt driveways is sinking spots or potholes. An asphalt driveway often sinks because the underlying dirt used wasn’t properly compacted or contains decomposing debris. Regardless of the reason for the sinking, without proper maintenance, an asphalt driveway won’t last the 25 to 30 years it should. Before repairing an asphalt driveway, check the condition of the driveway. Car tire impressions indicate poor construction. If there’s tilting or heaving in the winter, and buckling in the spring, you may have a drainage problem you must attend to before or after fixing the driveway.
Remove loose materials from the sinking spots. Use a broom to clean out materials like crumbled asphalt and debris such as rocks, sand and plant from the pothole. To remove excess debris, use an air or water hose until spot is clean.
Fill the pothole. Place crushed rock or gravel into the sinking hole. Stop when the crushed gravel is approximately four inches from the surface.
Apply patching material to the sinking spot with a broom. Spread the patching material throughout the pothole’s surface with an aggregate rake before letting the material sit for 15 minutes. Use a trowel or shovel to mix the asphalt into one-inch layers.
Smooth and compress the patch using a motorized packing machine or hand tamping method. The patch and original asphalt should be flush when the patch is properly compressed.
Block off the area. Use cones or tape to keep anyone from stepping or driving on the area while it dries. Curing, or drying, takes approximately three hours.
Place asphalt sealer on the entire asphalt driveway. Use a broom or roller to apply the sealer, then wait for about 24 hours before using the driveway.
You may want to use cold patches to fill large sinking spots in asphalt. When using the cold patches, repeatedly apply the patches, then tamp them down to stop air pockets from forming.
If your home is new, you may want to contact the builder. Your sinking asphalt driveway may be caused by an improper compaction of the subsoil and covered by your home’s warranty.
After filling the hole, sweep any extra sand, crushed rocks or any debris away from the surface. You don’t want to encounter the same problem with improperly compacted materials underneath the asphalt. Also, when moving excess debris using a water hose, make sure all the water is removed from the area before filling the sinking area.
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