Driveway drainage when paving in Oregon can be tricky, It is imperative that your driveway drains properly. Driveway drainage should drain across and off of your driveway or into a catch basin that gets piped away from your asphalt. If the water drains through your asphalt this is a problem, it can lead to base failure and alligatoring.
What caused the water to drain through your asphalt to begin with? Several things can cause this issue. Poor or Bad driveway drainage will cause base failure. If your asphalt driveway is not (both before and after paving) compacted properly or has an inadequate thickness of asphalt it can cause this to happen. Asphalt has to be hot when it gets compacted allowing all of the oil and rock to compress together (before it gets cold and stiff) filling any voids in the hot mix asphalt. The base rock must also be compacted before paving to compress all of the rock together so your have a good base to pave over.
Base failure can cause severe damage and greatly reduce the longevity of your asphalt driveway life expectancy. As water works its way down through the base material it starts moving smaller material away from the larger material creating voids. Voids in base rock will eventually fall away creating sinking areas and leading to alligatoring. This could have been prevented with proper driveway drainage This is called base failure and is due to poor base preparation. Base failure can be repaired but can be costly.
Driveway paving in Oregon can be especially tricky because of our relentless rain in the winter and spring. On top of base failure from water intrusion through your asphalt, you must also make sure you have an adequate amount of base rock. Our recommendation for any driveway that has a tendency to be in a fairly wet area is 8 inches of compacted base. This is the depth of base rock after compaction not before.
Asphalt cracking for alligatoring can also be caused from fatigue. This will also lead to base failure. Notice this photo you don’t see much sinking just a whole bunch of cracking. This asphalt has lived its life. Its time to replace it. This does not always mean overlay it. This asphalt pictured cannot be overlaid. This will need to be removed and replaced.