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Quick question about repairing an expansion joint in concrete

JC72 | Posted in General Questions on

The joint is about 3ft x ~1.5 inches and the gasket put in place by the builder is long gone. I plan to install a new gasket and top off with the appropriate caulk/sealant.

Since the gap has been neglected I anticipate having add fill with some sort of material.

Q: What material should it be? Sand or soil? I have an opened bag of potting soil that I could tamp down in order to raise the gasket to the correct height. I’m thinking maybe a half inch of fill.

Thoughts?

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Replies

  1. user-2310254 | | #1

    John,

    You can use a foam backer rod. This material is usually available at one of the big box stores or online.

    You also want to look for a high-quality polyurethane caulk designed to adhere to concrete.

  2. JC72 | | #2

    @Steve. That's what I was planning, but I was thinking in case the gap is deeper than the foam backer rod or does it matter that there's a little air space between the bottom of the backer rod and the soil underneath?

  3. GBA Editor
    Martin Holladay | | #3

    John,
    Sand would be ideal, but soil would work. If you don't know where you can get a handful of sand, home centers sometimes sell small bags of sand as "sandbox sand."

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