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RE: super flat floors

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To second the opinion about Kalman or any super flat specialty contractor.

Super flats require experience of an entire team including the design team. Taking on mix design and admixtures is daunting enough. You also need someone to baby sit the batch plant. Now you need to get a flat work crew who knows what they are doing. You need to make sure that it is screeded correctly and finished correctly. Don't forget the subgrade prep and the curing. You should also get a geotechnical engineer who knows how to build super flats in your area on your type of soil.

The designer who gets half way into the construction will get sucked all the way into the litigation.

Just put together the PERFORMANCE that you need and let a specialty contractor figure it out.

Harold Sprague

From: "Stuart, Matthew" <mstuart(--nospam--at)>
Reply-To: <seaint(--nospam--at)>
To: <seaint(--nospam--at)>
Subject: RE: super flat floors
Date: Fri, 8 Jun 2007 14:25:54 -0400

            That's o.k. as long as you are working with a reputable
specialty contractor like Kalman floors (
and understand that you will have to modify some of your typical
foundation details so that they can allow for the expansion of the slab
before the slab shrinks back to normal size.

Matthew Stuart

Structural Department


Extension 1283

-----Original Message-----
From: Michelle Motchos [mailto:mmotchos(--nospam--at)]
Sent: Friday, June 08, 2007 2:14 PM
To: seaint(--nospam--at)
Subject: RE: super flat floors

How about a type K or other shrinkage compensating mix with mild
reinforcement? I saw a presentation by Larry Valentine of ShrinkageComp
Plus last year that was interesting on the topic (
<>     704-785-0741)

Michelle Motchos, PE
Stevens & Wilkinson of South Carolina, Inc.

Columbia, SC


From: Dave Handy [mailto:dhandy(--nospam--at)]
Sent: Friday, June 08, 2007 11:15 AM
To: seaint(--nospam--at)
Subject: super flat floors

Good morning all:

Does anybody out there have experience with super flat slab on grade
floors. In our case we have an area of about 200' x 300' with racking
height of about 32'. We have spec'd a concrete strength of 25MPa (28
days) with steel fibres, 1 1/2" aggregate and a w/c of 0.55. We are not
experts in this fields and as a result are telling the people building
it the specs we require and are basically putting the ball in their
court. Initially we spec'd a 30MPa concrete with a 0.45+- 0.02 w/c ratio
but the concrete supplier said that this mix would crack too much. He
tells us that with the cement that they use and the low w/c ratio the
strengths would be in the 40+ MPa range and would cause a lot of
shrinkage. We are obviously trying to reduce shrinkage and thought that
the low w/c ratio along with a requirement for the design slump to be 1
1/2" with super-p being added to increase slump to the 5" range would
produce the least shrinkage. We are being told that a w/c ratio of 0.55
or even 0.6 is preferred by the concrete supplier.  The concrete
supplier says he takes no responsibility for the mix and has admitted
that we can't get guidance from others in different locales because the
ingredients are of differing qualities and chemistry than what we deal
with in our area.  I have an article from concrete international that
recommended 4000 psi with the 0.45+- 0.02 w/c ratio. The concrete
supplier has said that he has heard others in the US swear by this mix
however he said that if he produces this concrete with his ingredients
the strength is far too high and as a result there is more shrinkage
cracking.  There does some to be some consensus in what he is saying
based upon projects that have been done in our area. Water reducers
which I previously thought would reduce shrinkage are actually
increasing shrinkage??(according to ACI 360R-06) Why use them at all


What are the key elements that you would use to spec the concrete. We
need a final strength in the 4000 psi (28 MPa) range. There is only PC
type 10 and blast furnace slag as the cementitious components, the
aggregate is limestone. There are no post-tensioned slabs done in our
area. The floor people want to let the floor crack and will fill the
joints as long in the future as practically possible..perhaps 6
months..with epoxy.

any thoughts



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