Pavement Replacement

[trey25624]

I'm working on a job where we are redeveloping an existing gas station. Part of the scope is to replace all the asphalt on the job. This was due partly to the asphalt's condition, but mainly because I had to regrade the pavement to accomodate changes. I would like to avoid replacing the pavement full depth, meaning I would like to keep the base aggregate. What, if anything, should I be concerned about when reusing an existing base aggregate? My thinking is if we get a proctor on the material and make sure its compacted properly, we don't need to worry. I guess something makes me think you would need to remove it all or place it again.

 

[civilperson]

How do you keep a uniform thickness of base aggregate when changing the grades of the finish surface? If no changes are required in finish grades, milling a fraction of the asphaltic concrete and placing new surface layer is a normal proceedure for creating a new pavement.

 

[jmgray]

I agree w/ civilperson's post. If the change in grade is so great that it cannot be made up with an AC overlay, the existing AC can be ground & recycled. An attachment to a dozer/loader thats essentially a spinning drum w/ teeth will grind AC in place and mix it into your base rock. The area can then be regraded per design.

You should be aware, however, that the recycled AB may not meet the specs of your DOT. Because this is just a parking lot/gas station (and depending on the attitude of the local building agency) you may be able to increase the pavement section of the recycled material compared to virgin material (which is likely to happen annway by using the AC volume). Or if need be run sieve, duribility, r-value ect. testing to show if the material is in spec.

 

[dirtygeo]

I agree with the above comments. If only raising the grade a small amount place an asphalt overlay (taking care to properly clean and tack coat first). If raising the grade more than an inch or two then pulverise the existing asphalt to a depth of about 4 to 6 inches in to the existing granular base material. Provided the existing granular materials were of decent quality you will end up with a well graded granular base that should do the job of supporting asphalt while promoting good drainage. You can then raise to underside of new asphalt with Granular A and pave.

As for pulverised granular material meeting a spec, it doesn't need to on a private project (as in this case). If a public project it is a different storey (maybe).