Forensic investigation for loose aggregate
Forensic investigation for loose aggregate
(OP)
We have a newly constructed asphalt pavement that has a small isolated area (1ft by 3 ft) under left wheel path showed surface loss, mainly big aggregate loss. The initial thought after looking at the pictures are due to the gasoline spillage. Is there any lab tests we can use to verify this speculation? Thanks!





RE: Forensic investigation for loose aggregate
RE: Forensic investigation for loose aggregate
RE: Forensic investigation for loose aggregate
If the remainder of your mats (ACP pavt. area) test results, cores, % air voids, and overall appearance contains no other surface irregularities; this would most likely be a fuel, hyd. oil, or release agent spill.
We have found the culprit to routinely be a ruptured hydraulic line failure (leaks onto the mat) in most cases.
Your spec.s should include language to perform corrective actions on these areas irregardless of the source.
RE: Forensic investigation for loose aggregate
RE: Forensic investigation for loose aggregate
There seems to be a lot of raveled aggregate nearby...is that from the same depression or is it occurring overall? If occurring in a lot of areas, you might want to make sure your mix has adequate binder and that is was placed at the right temperature. Raveling can be caused by undercompaction, cold placement, low asphalt content, high voids, poor gradation, etc.
There are not any really inexpensive ways to conclusively test for the damaging material. Most aliphatic hydrocarbons are closely akin to asphalt cement, since it is one as well.
Fortunately, this is a relatively small area. The source could have been anything from a parked piece of equipment to the paving machine, though if the paving machine, you would likely see repetitive spots of the same condition.
Unless the owner has a lot of equipment or processes that might have contributed to this, it is unlikely you'll be able to tag him for it. The construction process usually has more opportunity to cause this type of damage than the owner; however, only field investigation and evaluation can tell that...not a forum response.
RE: Forensic investigation for loose aggregate
Just a guess.
Also, the fuel leaks/spills I have seen usually are very fat looking on top of the mat. This looks a little different.
Again, your contract language should include methods to remediate theses areas at no cost to the owner, irregardless of the cause. If not, this is a prime example of why spec.s should be incorporated into bid documents.
RE: Forensic investigation for loose aggregate
RE: Forensic investigation for loose aggregate
The problem area was in the middle of area paved that same shift. The chance for cantaminated load from truck is small since the truck should already be loaded a couple times before it returned to this area.