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RE: epoxy bonder and 1" topping slab in vehicle washing area

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Mathew is correct. A petrographic analysis is the only sure way to diagnose the cause of the spalling. A 1" concrete topping may actually exacerbate the problem. The parent concrete has been in place for some finite amount of time. The newly placed concrete will shrink differentially with the parent concrete.

That is not a trivial issue.

The concrete spalled for some reason, and you will not know why until you do a petrographic analysis. The 2 major causes of spalling in cold country is freeze thaw and no air entrainment or high water in the top of the slab (too wet of a mix).

This may help a bit.
http://www.knovel.com/knovel2/Toc.jsp?BookID=740

Regards,
Harold Sprague





From: "Stuart, Matthew" <mstuart(--nospam--at)schoordepalma.com>
Reply-To: <seaint(--nospam--at)seaint.org>
To: <seaint(--nospam--at)seaint.org>
Subject: RE: epoxy bonder and 1" topping slab in vehicle washing area
Date: Thu, 30 Mar 2006 17:53:11 -0500

Technical definition: Description and systematic classification of rocks. Read the recent article in Structure Magazine for its relationship to the study of concrete samples:

http://structuremag.org/archives/2006/January-2006/C-SP-Petography-Powers.pdf

Bottom line - you really need to know the disposition of not only what is the source of the problem on the surface of the slab but also the conditon of the concrete substrate that the Contractor wants to apply the epoxy binder to.

________________________________

From: Haan, Scott M POA [mailto:Scott.M.Haan(--nospam--at)poa02.usace.army.mil]
Sent: Thu 3/30/2006 5:41 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: epoxy bonder and 1" topping slab in vehicle washing area


Mathew:

For the ignorant what is a petrographic core?

Thanks.
Scott

________________________________

From: Stuart, Matthew [mailto:mstuart(--nospam--at)schoordepalma.com]
Sent: Thursday, March 30, 2006 1:31 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: epoxy bonder and 1" topping slab in vehicle washing area


I would recommend that you have a petrographic analysis done of some representive cores, otherwise you're just flying blind.

________________________________

From: Haan, Scott M POA [mailto:Scott.M.Haan(--nospam--at)poa02.usace.army.mil]
Sent: Thu 3/30/2006 5:24 PM
To: seaint(--nospam--at)seaint.org
Subject: epoxy bonder and 1" topping slab in vehicle washing area


I am involved with a project where a 6" slab on grade's surface finish was spalling. The breaks are between 4500 psi and 5000 psi. The contractor wants to grind down the top 1" and put an epoxy bonder on the ground down areas and then put on a 1" topping slab. The area will be wet and have vehicles park on it.

Has anyone heard of this kind of fix and is it durable over the long term? Should an extended warranty be requested?


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