100% compaction for aggregate basecourse/sub-base?
100% compaction for aggregate basecourse/sub-base?
(OP)
I'm writing an RFI requesting revision of a spec calling for 100% compaction on aggregate basecourses and sub-bases under asphalt paving and PCC paving. Anyone here ever required such a thing for base courses??
The state DOT standard only requires a 95% for all basecourse/sub-base. I'm looking for any other reasonable excuses other than thats just plain silly.
The state DOT standard only requires a 95% for all basecourse/sub-base. I'm looking for any other reasonable excuses other than thats just plain silly.





RE: 100% compaction for aggregate basecourse/sub-base?
RE: 100% compaction for aggregate basecourse/sub-base?
RE: 100% compaction for aggregate basecourse/sub-base?
I agree 98% is reasonable for crushed aggr. base courses that are with-in a pretty rigid spec. base.
As for subbases, not sure of the material(s) you are refereing too.
RE: 100% compaction for aggregate basecourse/sub-base?
RE: 100% compaction for aggregate basecourse/sub-base?
RE: 100% compaction for aggregate basecourse/sub-base?
f-d
¡papá gordo ain't no madre flaca!
RE: 100% compaction for aggregate basecourse/sub-base?
I've done most my projects out of the state of washington and never encountered a 100% compaction spec.
RE: 100% compaction for aggregate basecourse/sub-base?
Compacting to 100% takes out most of the additional compaction that will be done by traffic. Not such a big deal with rigid pavement, but can be significant with flexible pavement. Further, if subbase or subgrade soils require bridging in any fashion, a higher stability and compaction in the base will be necessary.
My point is not to summarily dismiss the compaction requirement. If done for considered reasons, it is a responsible requirement.
RE: 100% compaction for aggregate basecourse/sub-base?
RE: 100% compaction for aggregate basecourse/sub-base?
RE: 100% compaction for aggregate basecourse/sub-base?
if you think 100% (modified/standard?) is excessive, then recommend something else based on your lab testing, design experience, pavement design criteria, owner's expectations, etc etc. it's your stamp and liability.
RE: 100% compaction for aggregate basecourse/sub-base?
RE: 100% compaction for aggregate basecourse/sub-base?
RE: 100% compaction for aggregate basecourse/sub-base?
RE: 100% compaction for aggregate basecourse/sub-base?
The other aspect of this question that isn't being asked is what is the classification of the subgrade material? CL,..CH?..SP? I know a case where 95% compaction was specified for a CH subgrade and CL. II AB beneath concrete paving..the result was a suit when the subgrade swelled and the concrete cracked. Subgrade material type is important.
I'm surprised both by some of the responses from other states, and in that anyone would specify 100% compaction. Not because its impossible, but rather because it seems impractical. If Std proctor...ok...but still awkward. If modified proctor, why as an engineer or agency would you want to hold the contractor to such a high standard? Also, for aggregate, the range of moisture over which 100% could be achieved would be fairly narrow,on the order of a couple of percent.
I'm curious as to how 100% compaction is monitored; what will be expected from the field engineer under such a spec? For example - when confronted with test results suggesting 104% compaction..or even 99% has been achieved must he fail the lift and advise the contractor to rip it, and do it again until exactly 100% is achieved? In the former case where several tests exceeded 100%, would he properly obtain a bulk sample and run another lab compaction test to determine the new 100% (max dry density value)?..or simply accept the values exceeding 100% as acceptable when clearly the composition of the material has changed...? Or perhaps this is a case where close adherence to such things is not the norm, and testing is performed over an area, the tests averaged and if 100% is achieved the lift passes?
RE: 100% compaction for aggregate basecourse/sub-base?
Remember that the max dry density value as determined by the standard or modified proctor is just one such max value, i.e. it is not "the maximum density" of the material. Therefore, it is possible to have over 100% compaction when compared to the proctor.
We typically specify 100% of the standard proctor for aggregate base material. We use the standard proctor for base because we found that the higher energy of the modified proctor test resulted in crushing of some of the aggregate creating a result that did not match field observations for placed material.
Mike Lambert
www.shannonwilson.com
RE: 100% compaction for aggregate basecourse/sub-base?