AC Parking Lot - Grind/Deep Lift/Overlay
AC Parking Lot - Grind/Deep Lift/Overlay
(OP)
I am supervising a job which has as part of the scope of work the re-surfacing of an old AC parking lot. The existing parking lot is approximately 4" of AC over about 6" of base rock. The subgrade soil profile is thick, firm adobe clay. There is a lot of aligator cracking in the existing pavement, which has been further exacerbated due to large number of heavy trucks going over it during adjacent construction activities we are doing. The specs call for a 2" grind throughout the parking lot, then a 2" AC overlay with 3/8" AC. We are doing deep lift sections on some areas of the parking lot, but there is not enough money in the budget to do it on all of the bad areas. We are also using fabric under the overlay.
I was wondering if anyone can comment on past experiences on the performance of overlays in general and more specifically over areas where the underlying existing AC has extensive cracking already. Also, any tips you have to assist me during inspection of the grind and overlay would be appreciated. Thanks!
I was wondering if anyone can comment on past experiences on the performance of overlays in general and more specifically over areas where the underlying existing AC has extensive cracking already. Also, any tips you have to assist me during inspection of the grind and overlay would be appreciated. Thanks!





RE: AC Parking Lot - Grind/Deep Lift/Overlay
RE: AC Parking Lot - Grind/Deep Lift/Overlay
RE: AC Parking Lot - Grind/Deep Lift/Overlay
As an alternative solution, he has suggested eliminatiing the 2" grind and doing a levelling course along with a geotech fabric/grid over the existing AC. Then we would do a 2" or 3" AC overlay over that.
RE: AC Parking Lot - Grind/Deep Lift/Overlay
In my experiance 4" of asphalt over 6" of base is an unusual design. I'm more use to seeing 10"-12" of base and 3"-4" of asphalt, especially if there is truck traffic. A lot has to do with the subgrade but, the compacted base is cheaper than the asphalt and able to support more load. I think you would be better off stipping the existing asphalt, recrushing it for base, add some new base and end up with the 10"-12" thickness. Then put the asphalt down. The life cycle cost of this would be a better investment.
That's my two cents.
RE: AC Parking Lot - Grind/Deep Lift/Overlay
RE: AC Parking Lot - Grind/Deep Lift/Overlay
1) Eliminate the 2" grind and 2" overlay
2) With the cost savings from elimination of the grind and overlay, we are going to be able to deep lift almost all of the badly cracked areas.
3) Then we will do a seal coat over the entire area.
I think this is the best solution given my cost constraints. Thanks again for your input!
RE: AC Parking Lot - Grind/Deep Lift/Overlay
I suggest doing gradation and sand equivalent tests on your existing base course. If it has to many fines, cement stabilization or emulsion stabilization may help. Then again, grinding up the asphalt and mixing it in may help, if you make sure not to grind it into fines.
RE: AC Parking Lot - Grind/Deep Lift/Overlay
RE: AC Parking Lot - Grind/Deep Lift/Overlay