That is, if you get some higher than the specified relative compaction (or relative density in some cases) results and some lower, use of engineering judgement is of great importance when accepting the work completed. Great points gentlemen! When dealing with compaction testing and acceptance criteria, you really need to keep the idea of the statistical density of a compacted fill based on the testing done. RE: Why 95% Compaction jheidt2543 (Civil/Environmental) 14 Jun 03 10:50
It is a matter of experience, personal prejudice, etc.Ī guy named Moynihan - a prof at a school in NJ - wrote a damn good book on compaction. I won as I was senior and had to sign off on the report - but this shows that there are good arguments on one side or the other. I countered that the use of "modified" - at least to the contractors in our area - tells the contractor that more care is needed in the fill placement and compaction. He argued that "most" of the soils labs did standard as a matter of course (and the modified was, like I indicated above - a hernia test). I was leaning on him to accept 95% Modified Proctor. The fill was to support some lightly loaded to moderately loaded foundations using good engineered fill. He insisted on specifying 100% Standard Proctor (light tamping, roughly). I once had an argument with a junior engineer in our company. There was a fine paper written in Ground Engineering on the "95% Fixation" - I have a scanned copy I would be happy to send out (if my serer will allow the size - but I can send page by page). I believe too that the 95% was put out by someone years ago and 'ell, it's here to stay since engineers just crop specs from one site to another - for the most part. Some people just like things to be "heavier" - the bigger the better. I've used 95% standard with no problems elsewhere. Here in India, MOST requires 95% of the MDD of Heavy Tamping (similar to the Hernia Test - oops, the Modified Proctor) for embankments. MRM - yes, 95% is typically done in that way - still, would 94% be okay? When constructing, people get bent all out of shape if you don't reach the 95% value.
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