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RE: Tolerable Slab Design

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I am going to swim upstream with my engineering brethren on this one. I have designed a lot of structures on the Front Range of Colorado. And 2" in ?? feet is not much soil swell in that neck of the woods. They rarely do PT floor slabs on large industrial floors. They are done, but it is rare.

The best in the business out there is Kalman Industrial Flooring located in Evergreen, CO and they do work nation wide. I would give them a call.

The do a floating slab. I did one in Golden, CO that was about 600' x 600' with Kalman. The columns were in about a 30' grid. The trick is to put in "some" rebar. Just enough to hold it together for shrinkage, and let the slab float. There are no turn downs anywhere. You allow the slab to float on the soil with joints at about 100' each way. The columns are treated like penetrations with closed cell foam around them to accommodate concrete shrinkage.

The Kalman slabs look great many years and seasonal cycles later. And they are adjacent to another facility that have typical slabs with all the cut joints and 30' spacing, and those look horrible.

Keep in mind 2" in 100' is nothing for any slab.  2" in 1' is a problem.

Harold Sprague

From: "seaint03" <seaint03(--nospam--at)>
Reply-To: <seaint(--nospam--at)>
To: <seaint(--nospam--at)>
Subject: Tolerable Slab Design
Date: Wed, 28 Sep 2005 12:23:38 -0500

I received a geotechnical report to review for a foundation design for a pre-
engineered metal building.  It is a warehouse type building with lots of
open spaces.

The building is located on expansive soil.  One of the items in the report
states to "design the slab to tolerate potential upward slab movement on the
order of about 2 inches of active swell".  I don't recall ever seeing a
design procedure for designing a slab on grade to accommodate upward slab
movement of any amount.  IS there some design procedure I am not aware of?
Can anyone cite a reference I can research to help understand it?

What are others commonly doing to design a warehouse type slab, large open
spaces, for upward movements?  My thoughts are frequent shrinkage and
construction joints to isolate slab panels and facilitate replacement if

Thanks for any insight.


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