Legal Aspects of One-Point Proctors
Legal Aspects of One-Point Proctors
(OP)
I want to institute the use of one-point proctors performed in the field for our company. We would use AASHTO T272 (Family of Curves) and ASTM D4959(Direct Heat Moisture Content)as guidelines. We want to use one-points to verify proper proctor selection.
The problem is that I have some managers who are saying that if we don't do everything per ASTM, like we do in the lab, that if a project ever goes to court then we would have a liability issue with the one point proctors.
Does anyone have some suggestions how I approach these managers so that I can get them to buy in to use of one -point proctors?
The problem is that I have some managers who are saying that if we don't do everything per ASTM, like we do in the lab, that if a project ever goes to court then we would have a liability issue with the one point proctors.
Does anyone have some suggestions how I approach these managers so that I can get them to buy in to use of one -point proctors?





RE: Legal Aspects of One-Point Proctors
To me the benefit of a one-point Proctor is to pound a point and see if it falls on one or the other of the two curves that you already have. If it's somewhat higher then the dry limb, you may want to sketch in a curve that's roughly parallel to the lab curve and peakes at the line of optimums. You may want to use this fabricated maximum dry density as a basis to either accept or reject the compaction test. If you really have an interpolated maximum dry density that is different from one of your curves, you may make a provisional approval, but submit the sample for a lab curve. If you get another lab curve, you may want to add it to the two proctors you already have and better define the LOO for future tests.
I don't like the wet-density family of curves, even though they're widely used. It's just too easy to make your own family of curves for your local work areas.
It's nice to know you actually care about the adequacy of your field data. I'd rather see quality checks via one-point proctors then somebody just relying on the gray-dirt proctor and the red-dirt proctor, both done to the requirements of the ASTM.
f-d
¡papá gordo ain't no madre flaca!
RE: Legal Aspects of One-Point Proctors
RE: Legal Aspects of One-Point Proctors
RE: Legal Aspects of One-Point Proctors
I have to comment on BigH's post too: While I'm not familiar with this method, I do like an approach that solves the problem. Whether ASTM has a "Standard" for that approach is irrelavent, if the engineer using the data is standing behind the analysis.
f-d
¡papá gordo ain't no madre flaca!
RE: Legal Aspects of One-Point Proctors
RE: Legal Aspects of One-Point Proctors
I'd not use it, especially if the job is "touch and go" as to being adequate in meeting specs.
On the other hand, I have modified my ways in later years by calling for much less in the way of degree of compaction, consistent with knowing what the job needs are. For instance, if you are on a paving job and your site has both cut and fill, if your cut area naturally has a clay soil at 85 percent compaction and a Qu of 1.5 t/sf, why would you specify 95 percent compaction at the fill area? Sometimes a common sense approach gets just a good a job at less cost and less fighting.
RE: Legal Aspects of One-Point Proctors
RE: Legal Aspects of One-Point Proctors
There was a time when the US Army Corps of Engineers required a FULL proctor with each in-place density test. Kind of reminds me of...
Measure with a micrometer, mark it with a crayon, and cut it with an axe.
RE: Legal Aspects of One-Point Proctors
RE: Legal Aspects of One-Point Proctors
Completly disagree! Incorrect use of a family of curves is wrong. Here's my perspective: There is little value in some "Ohio" family of curves right here in Virginia. That said, if you are working on a project with LOTS of earthwork, you may end up with six, eight or 10 Proctors during the course of the project. Use these proctors to make YOUR OWN family of curves. Do confirmation testing at a Field density test location via a one-point (on the dry side) and compare it to your family of curves. That's what I consider good practice - nothing wrong with good practice. And, it beats the heck out of the more typical guess work. It's the guess work that ends up causing great pain after the wall falls over, the pavement fails, or the instructrial floor slab cracks.
end of rant. . .
f-d
¡papá gordo ain't no madre flaca!