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RE: Sulfates

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William,

As I tried to imply, ASTM D516 can not be directly used for finding the concentration of sulfates in soils.  A good geotech/laboratory should be able to give you the correct results as long as they know what you are looking for and what you are going to use the information for.  I have never had a problem getting this information before.  However, if you are looking for a tighter specification you could reference one of the following:

1. DOT CA test 417/Part II (Turbidimetric Test)

2.  EPA 0300.0

3.  County of Orange Modified Test Method (10:1 Dilution/Gravimetric Test)

Thomas Hunt, S.E.
ABS Consulting




"Sherman, William" <ShermanWC(--nospam--at)cdm.com>

08/30/2002 11:14 AM
Please respond to seaint

       
        To:        "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
        cc:        
        Subject:        RE: Sulfates



Tom, thank you for your response.

Regarding using ASTM D516 to test for sulfates, the ASTM states that the
test method covers "water in the range from 1 to 40 mg/L of sulfate ion".
This equates to 40 parts per million (ppm) or 0.004 percent sulfate ion
content. But we are concerned with sulfate contents in excess of 0.10
percent in soils or 150 ppm in water. Thus, how can this test be used to
confirm sulfates in the range we are interested in?


-----Original Message-----
From: THunt(--nospam--at)absconsulting.com [mailto:THunt(--nospam--at)absconsulting.com]
Sent: Friday, August 30, 2002 8:32 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Sulfates

William,

1.  It is unlikely you will find any maps on sulfate content of soil.  It
can vary from street to street and can come from many types of sources
including water leaching, farming, contamination, and naturally occurring.
For a general idea you could call several geotechs and/or testing
laboratories in the area.  If you have control over the geotechnical scope
of work I would always include sulfate and chloride testing.  The reason for
this works both ways.  Geotechnical reports will always recommend Type II
cement just to cover their butts.  The last several reports I reviewed I was
able to challenge them on this based on their own testing and got them to
allow Type I.  Any good geotech should understand how to include sulfate
testing in their report.

2.  Specifying Type II is almost a standard now for fear of being sued
latter in life.  If you have the test data then it is pretty simple to look
up the requirements in ACI 318 Table 4.3.1.

PCA performed a lot of testing back in the late 1980's and authored a report
called "Durability of Concrete in Sulfate-Rich Soils".  I am not sure if it
is still available.  They tested different w/c ratios, cement contend,
cement types, mineral additives, etc.  The big conclusion was that with a
w/c of 0.40 or less the cement type had no effect.  This was also true of
w/c ratios above 0.55.  The mineral additives all improved sulfate
resistance with silica fume being the best.

3.  ASTM is in the process of developing a new test for sulfates in soil but
for now you can specify ASTM D516 and they should be able to get you what
you want.

Thomas Hunt, S.E.
ABS Consulting

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