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.
Regards,
Harold Sprague
>From: "Stuart, Matthew" <mstuart@schoordepalma.com>
>Reply-To: <seaint@seaint.org>
>To: <seaint@seaint.org>
>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 (http://www.kalmanfloor.com/)
>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
>
>Manalapan
>
>Extension 1283
>
>
>
>-----Original Message-----
>From: Michelle Motchos [mailto:mmotchos@sw-sc.com]
>Sent: Friday, June 08, 2007 2:14 PM
>To: seaint@seaint.org
>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 (www.shrinkagecomp.com
><http://www.shrinkagecomp.com/> 704-785-0741)
>
>
>
>
>
>Michelle Motchos, PE
>Stevens & Wilkinson of South Carolina, Inc.
>
>Columbia, SC
>
>________________________________
>
>From: Dave Handy [mailto:dhandy@trg.ca]
>Sent: Friday, June 08, 2007 11:15 AM
>To: seaint@seaint.org
>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
>then?
>
>
>
>So...
>
>
>
>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
>
>
>
>thanks
>
>Dave
>
>
>
>
>
>
>
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