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RE: Trash Transfer Station

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I share your concern.  I have seen more degradation of control joints than anything.  Unless there is a joint in the substrate, I would opt not to have control joints.  I would do all that I could to bond the slab well.  I would scarify the surface, bond the topping well, evaluate the topping to minimize shrinkage, and do a wet cure of the topping in accordance with the ACI 308R. 
Unless a joint is cut within 6 hours, it will not be effective.  The concrete will have already cracked.  Tooling or a Soft Cut saw are the only effective ways to joint a slab.  But as I stated before, I would be inclined to eliminate control joints if at all possible.   

Regards, Harold Sprague


From: MStuart(--nospam--at)
To: seaint(--nospam--at)
Date: Fri, 30 Jul 2010 07:49:59 -0400
Subject: Trash Transfer Station

I’m in the process of putting together some bid documents for the repair of a severely eroded framed slab at a trash transfer station. We will be milling the top of the concrete down and going back with a mineral aggregate topping (L&M Emerytop 400) of 1½ to 2 inches in thickness.


The material supplier has recommended that we provide control joints at least 12 feet on center in the topping and I am concerned about the durability of any sealant we fill the CJ with.  In addition, I am debating whether a tooled CJ or a sawn CJ would be less susceptible to the wear and tear environment of the trash tipping floor.


Any input would be appreciated.


D. Matthew Stuart, P.E., S.E., F.ASCE, SECB
Structural Division Manager

Pennoni Associates Inc.
One Drexel Plaza
3001 Market Street, 2nd Floor
Philadelphia, PA 19104
Office 215-222-3000 x7895 | Direct 215-254-7895
Fax 215-222-0789 | Mobile 908-309-8657 | mstuart(--nospam--at)


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