Select Fill Materials
Select Fill Materials
(OP)
Could someone help me in understanding the term "Select Fill" materials. I understand these fills are not expansive and can substitute the expansive soils in order to decrease the potential vertical rise of the sub-grade soil due to moisture variations. What are the typical ingredients of select fill materials. I presume they are sand and clay. How many percent clay do they have? Thank you.





RE: Select Fill Materials
RE: Select Fill Materials
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RE: Select Fill Materials
f-d
ípapß gordo ainÆt no madre flaca!
RE: Select Fill Materials
RE: Select Fill Materials
RE: Select Fill Materials
RE: Select Fill Materials
RE: Select Fill Materials
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ípapß gordo ainÆt no madre flaca!
RE: Select Fill Materials
https://flh.fhwa.dot.gov/resources/specs/fp-14/fp1...
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ípapß gordo ainÆt no madre flaca!
RE: Select Fill Materials
RE: Select Fill Materials
https://www.wbdg.org/FFC/DOD/UFGS/UFGS%2031%2000%2...
https://www.wbdg.org/FFC/DOD/UFC/ARCHIVES/ufc_3_22...
RE: Select Fill Materials
As an example, if one has an highly expansive foundation material, removal and replacement with compacted lean clay may be a better solution to keep water from the expansive soil foundation than sand as an example. Usually a LL and PI requirement would be specified and possibly expansion/swell testing to confirm that the material does not have the same problem as the material being replaced.
TX, CO, KS, MS all have their issues with expansive & fat clays so I would look in those areas for local standards of practice regarding foundation treatment in expansive soils.
RE: Select Fill Materials
One more aspect of expansive soils that I have been looking for is the estimation of uplift pressures on the bored pile's skin, when the dry soil swells. I very much appreciated a feedback on this subject, too, if possible.
RE: Select Fill Materials
This may have some swell potential, but much less than the CH it may be replacing. Materials used are often sandy clay or clayey sand.
We will amend the specification to meet the particular needs of the project.
RE: Select Fill Materials
On a project with federal DOT funding, there is a likelihood that, "Select Fill" is as defined by the FHWA. I've provided that link. On jurisdictional or private projects, I'd agree that there is local convention that may allow such select fill to include USC classifications, CL, or ML, or other? Clearly in private practice, the specifying engineer can define it at will. Nobody in DOT work would defer to such local custom; however, as the FHWA definitions would prevail.
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ípapß gordo ainÆt no madre flaca!
RE: Select Fill Materials
RE: Select Fill Materials
RE: Select Fill Materials
I am still looking for the uplift pressure estimation - theoretical or empirical values. Das textbook has a section on this but it is complicated and I guess overestimates.
RE: Select Fill Materials
http://web.mst.edu/~rogersda/expansive_soils/Vario...
RE: Select Fill Materials
RE: Select Fill Materials
RE: Select Fill Materials
My associate confirmed that local practice (Dallas area) is some variation on about 1000 psf upward skin friction or adhesion applied over the depth of seasonal variation (commonly about 10 to 15 feet). He prefers a higher skin friction applied to about 2/3rds of the seasonal variation.
In dry weather, the undrained strength of our clays can be much higher than 1000 psf. But is the soil swelling and heaving at that time? Has the clay in the top few feet shrunk away from the wall of the pier? In wet seasons, will it both swell and soften from the top down?
Like a lot of rules of thumb, the practice generally seems to work most of the time. I would be cautious about applying it in other parts of the country.
RE: Select Fill Materials
RE: Select Fill Materials