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RE: Permissible Sulfate Content in Concrete

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You really need to get some definition on the sulfate concentration.
Sulfate concentrations in soil samples are as follows:
Negligible	0.00 to 0.10
Moderate 	0.10 to 0.20
Severe		0.20 to 2.00
Very Severe	2.00 or greater

What is evaluated is the water soluble sulfate in soil as a percent of the
sample weight.  If the guy providing the testing has any experience, he
should have given you the correct data.

You need to look at Sec. 4.3 on sulfate exposure and remedies.

The correlation you ask for does not exist.  The concrete degradation is
time and temperature dependent.  Given enough time, your piles will go away
entirely.  If it is hot, they go away faster.  ...How's that for vague?

You can find commentary and references in ACI 318 Sec. 4.3.  You might also
want to pick up a copy of the Concrete Manual by the Bureau of Reclamation.
They have a good section on sulfate attack.  They should, they are based in
Denver where they have many hot sulfate areas.

If you need any more definitive information, let me know.

Regards,
Harold O. Sprague

> -----Original Message-----
> From:	John Joman [SMTP:jojoman34(--nospam--at)yahoo.com]
> Sent:	Wednesday, January 09, 2002 11:34 AM
> To:	seaint(--nospam--at)seaint.org
> Subject:	Permissible Sulfate Content in Concrete
>
> Here is a question for all you concrete experts out
> there.  I have received some preliminary test results
> from concrete specimens taken from the piles of an
> existing building.  Results indicate that sulfate
> contents range from 0.5% up to 2.5%.  (Not sure if
> this is by total weight of specimen or by total weight
> of cement).  It was also reported that chunks of
> concrete could also be removed by hand at some
> locations.
>
> I understand that sulfates reacts with the calcium in
> the concrete to slowly degrade the cement matrix.   My
> question is, what percentages constitutes a  mild,
> moderate, and severe exposure?  Chapter 4 of ACI does
> provide maximum permissible chloride contents in
> concrete, is there a similar table for sulfates?  Is
> there any correlation between sulfate content and
> reduced concrete strength (i.e. 5% sulfates equals a
> loss of 10% in concrete compressive strength).
>
> If anyone can provide some useful references or
> insight into this matter, it would greatly be
> appreaciated.
>
> Thanks.
>
> John
>
>
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