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RE: Sulfate bearing soil

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Call your local cement suppliers, and concrete ready-mix suppliers.  You are
probably not the first one to get into sulfate soils.  Ask if they have some
off the shelf mixes that were tested per ASTM C1042.  They will probably
have some F ash blends with Type I-II cements.  

There is also an admixture called Durapoz that has shown to be very
effective in sulfate resistance.  Call Ash Grove cement for more

Cement in general is scarce.  Type V is even more rare.  The last I heard
there was only one plant in the US producing a true type V.

Sulfates will migrate in the presence of water.  You might get lucky and
only have a spot or 2 that is the only source
of sulfates, but then again you might not be lucky.  Even the 0.20% is
categorized as severe exposure.

I would get my sulfate resistance in the type of cement, admixtures, and in
the mix design itself (low w/c ratio, low slump, uniform aggregate blend,
good consolidation, increased cover, etc.).

Harold Sprague
The Neenan Company

-----Original Message-----
From: JCohen [mailto:jccpc(--nospam--at)]
Sent: Thursday, July 01, 1999 12:42 PM
To: seaint(--nospam--at)
Subject: Sulfate bearing soil

I recently had a soils test done for a propsective residence. The sulfate
content came out at between .15 and .20 % by weight of soil, excpet for 1 of
9 samples which tested at 3.7%. I have asked the testing laboratory to
confirm their results, as this was also sampled within 3 feet above and
below other samples which tested at between the .15 and .20 %. The pH was
also down on this single sample to 3.5, whereas the other samples were
around 5.1 to 6.5. My question is: would it be enough to remove high sulfate
content  locally from around the foundation without resorting to Type V
cement with added pozzolans? Are there other methods to avoid sulfate or
acid attack? If the test results are correct, and I hav enot reason to
believe they are wrong, it also appears that the sulfate is not migrating.

For information, there was a significant amount of debris found in the trial
pits at 8 to 12 feet below the surface. The site was a former horse track
with a pond, which was filled in. The locations of the track and pond are
not known, but are likely to be in the vicinity of the pits. Safe bearing
capacity has been estimated at 4500 psf.

Thanks for any suggestions.

James Cohen
James Cohen Consulting, P.C.