compaction testing in a wet trench
compaction testing in a wet trench
(OP)
i have a promblem in which this forum might be able to help. I am a contractor which installs infastructor for new subdivisions. i have run into a promblem that the compaction tests with a nucular gauge have failed do too too much moister(as much as 16%) when the pipe bedding was first put in it was dry and packed well. there was no compaction tests done at that time and now the municipality wanted that section dug up and tested .When tested it fails the nucular test do too high moister content. now the municipality has rejected the work and wants it dug up and redone. Is there another kind of test or a way around it?.(the rest of the job was tested in the dry and passed when dug up resently it also was too wet and failed)





RE: compaction testing in a wet trench
RE: compaction testing in a wet trench
There are soils that are affected by additional moisture after compaction...usually swelling clayey soils.
Also, keep in mind that compaction and stability are two different parameters. You can achieve compaction but still have stability issues, particularly if the soil is wet of optimum.
I agree with OG....get a local engineer out there who routinely does testing.
RE: compaction testing in a wet trench
RE: compaction testing in a wet trench
RE: compaction testing in a wet trench
There may be some problem with the testing details. With the various materials used for backfill, it may be possible that the technicians do not compare the trench tests to the proper laboratory tested material for each individual field test. A thorough testing program would run one laboratory test for each field test. That usually is not possibly so some judgement is needed in selecting the proper lab result to use for the field work. That is where many an argument can come up on the job. A competent testing job is required for these circumstances. Also, knowing the failings of the nuc method is needed by the testing firm.
RE: compaction testing in a wet trench
Is the material actually wet, or is it merely testing wet?
Did the tech doing the nuke testing use the proper offset for trench moisture? Nuke moisture tests taken in a narrow trench will show higher than actual moisture due to the presence of the moisture in the side walls of the trench. The Instruction for the nuke gauge should cover this.
Do I correctly understand that the nuke tests are being done now, after the material was placed, and then compacted. Now it is being excavated again, and those are the tests that are failing? Would it not make more sense to use another method to determine the actual moisture--as in taking a sample to the lab for an overnight oven-dry moisture test? at least before re-doing all that work.