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RE: Cement Certifications

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Fineness is a big deal with regard to heat of hydration.  The C150 is pretty
loose in this regard.

In this country the C150 cement is self policing because of the cement
shortage.  Our cement producers want to grind it as little as possible (time
is money).  In foreign countries they tend to grind C150 Type II longer and
finer to get it to hydrate like a Type I and thus the Type I / II
certification is a finer grind.  The only out is to limit the heat of
hydration within the C150 which will result in a more coarse grind.

The best option is to drop the C150 all together and switch to the C1157
specification and performance specify the cement.  There are a lot more
options in the C1157 as opposed to the C150.  You can fine tune the heat of
hydration performance aspect.

Harold Sprague

> -----Original Message-----
> From:	Lutz, James [SMTP:JLUTZ(--nospam--at)]
> Sent:	Wednesday, October 11, 2000 11:21 AM
> To:	seaint(--nospam--at)
> Subject:	Cement Certifications
> I have recently reviewed a couple of cement certification submittals from
> ready-mix suppliers with analyses reports saying the cement meets ASTM
> C150
> for Type I or II, but the fineness is testing close to double the limit
> for
> Type I or II, which would kick it into Type III (high early) territory.
> Some
> of this cement is imported from China. 
> I work with hydraulic structures where keeping the heat of hydration down
> is
> important to minimize overall shrinkage. The finer cement reacts more
> rapidly and generates more heat, which is undesirable.
> ASTM C150 has no limit on fineness for Type III, and I was wondering what
> typical values are, and whether I should be unduly alarmed about this. 
> Jim Lutz
> E
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