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RE: CONCRETE: Opinions Wanted - Joint Sealant for New Concrete to Existing

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I have developed a myriad of joint details over the years. They vary depending on the occupancy, traffic, expansion or contraction, size, etc.

Specifically to your question, I generally prefer Sika or Pecora My preferences evolved from a lot of input from applicators, contractors, and my own personal experience. I like the Pecora Dynatread type products and the Sika Polyurethanes. For a joint, the key is to provide a prepared perpendicular surface for adhesion. A bond breaker should be along the bottom parallel surface. The US Army Corps of Engineers has developed a standard on joint sealants that is helpful.

The other key ingredient is to inspect the joints doing destructive random testing. Read the product literature with all of the caveats. Aspect ratios are critical. After the inspector (ideally you) is satisfied, require the manufacturer to inspect and accept the installation.

I will almost guarantee that you will have some problems with applicators getting it right the first time. But once they understand that you are going to inspect a project even if it is from a swing stage 200 feet above the street, and you will reject non-compliant installations, the installation will be good.

I had a contractor once tell me that in 30 years of business, I was the first engineer or architect that went up on the swing stage to perform inspections 20 floors up. He was accustomed to NOT doing it right. He had budgeted one year of sloppy installation not in compliance with the specifications. The project took him 3 years to complete once he tore out all of the joints he did in the first year and re-sealed them the right way.

Oh yeah, you might want to go through the OSHA Fall Protection Course before riding the swing stage.

Harold Sprague

From: "Bill Polhemus" <bill(--nospam--at)>
Reply-To: <seaint(--nospam--at)>
To: <seaint(--nospam--at)>
Subject: CONCRETE: Opinions Wanted - Joint Sealant for New Concrete to Existing
Date: Sat, 18 Sep 2004 20:38:53 -0500

I have quite a few instances where I am casting a new slab-on-grade
foundation alongside an existing. I typically use a detail that allows
expansion/contraction but no "shear" movement either vertical or horizontal.

I'm content with that, but I wonder if my SEAL detail is adequate.

I'd like some opinions as to joint sealants you specify in such cases, and a
description of the detail. I'm always looking to "upgrade" my thinking on
any subject, and realize we tend to do what we've been doing for the last
twenty years out of laziness (okay, so that describes me at least, what can
I say?)

Let me know if you're partial to any specific product or formulation, and
state why. Also, do you have a different approach for a "dried-in"
application as opposed to one exposed to the weather?

Looking forward to soliciting your thoughts.

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