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Concrete poured and no control joints cut – too late now?

This topic contains 8 replies, has 6 voices, and was last updated by  kurt@welkerhomes.com 2 months, 3 weeks ago.

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  • #669829

    Hi all,

    I just had a bunch of concrete work done (retaining wall, 2 pads, driveway expansion, and more). The guys that I hired did NOT cut any control joints (AKA contraction joints). The pouring was finished about a month ago. I knew that they didn’t cut any control joints, but I thought that I could either just do it myself or hire someone else to do it sometime later.

    I’ve now done some searching and reading on control joints. Apparently these joints are typically cut in the first 24 hours. From what I’ve read, it sounds like if you cut these joints “too late” (after 24 hours) then they will have no effect on uncontrolled cracking. At the same time, it sounds like the main purpose of these control joints is to control cracking that starts during the initial curing, not after it has already cured.

    Since this concrete has now gone ~30 days of curing, is there any purpose to cutting control joints now? There are no cracks anywhere yet. I’m hoping a concrete professional can advise what I should do.

    Thanks for reading 😀

    #669842

    rerun_1965
    Pro
    holladay, TN

    the control joint is there so if the floor does crack it will stop at the joint so its never to late to cut one in

    #669870

    DirtyWhiteBoy
    Pro
    Honolulu,, Hi.

    How big is the slab or slabs??

    Dirty

    A Working Pro since 1988!

    Member since January 26, 2013.

    #669880

    The slabs vary in size:

    One 12 x 14
    One 10 x 12 (and varies from 4″ thick to 10″ thick due to grade change)
    One 8 x 80

    Thanks!

    #669888

    kurt@welkerhomes.com
    Pro
    Owatonna, MN - Minnesota

    the first two are on the threshold on not needing anything. the third probably does. I would cut that one at every 10 feet, even now. there are probably some shrinkage cracks already formed and probably more that will. cutting it now could help control future cracking. but there are no guarantees.

    #669891

    jponto07
    Moderator
    Bloomington, IN

    @kencobbing Have you tried calling the contractor? What did he say??

    Jon P.
    Timber Carpentry & Construction
    https://www.facebook.com/timbercarpentry/
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    #669913

    Sprokitz
    Pro
    Eastern shore of, Pa

    Agree with Kurt, the 2 big slabs may be OK. Is there any rebar, wire mesh or was a fiber reinforced mix used ? Those would be a plus. Are those free to move or are they trapped ? Do they abut other masonry, if so they should have expansion joints.
    I wouldn’t hesitate to cut control joints in the long one. Should be 1/4 as deep as the thickness of the slab. Ease the edges and fill with self leveling joint sealer. Idealy that long one should have alternating control and expansion joints.

    #669983

    Thanks for the replies 🙂

    @jponto07: I will not ask the company that did this work to come back to cut joints. His work was horrible. The lack of control joints was the most minor problem.

    @sprokitz: I insisted that he use wire mesh (which I already had on site for him) but I also know that he did NOT put it in because when I asked him he told me so, claiming it was unnecessary and overkill.

    The long stretch is abutted by the original driveway and house slab on one side and a new retaining wall on the other. In other words, the 80′ section buts against concrete the whole way down.

    Is there any chance that the long 80′ section won’t crack with no joints cut?

    The main thing I’d like to understand is: are control joints intended to stop shrinkage cracks from shrinkage that occurs during the initial cure? If so, why would they be useful at this stage, when it is 99% cured?

    #669996

    kurt@welkerhomes.com
    Pro
    Owatonna, MN - Minnesota

    Thanks for the replies 🙂

    @jponto07: I will not ask the company that did this work to come back to cut joints. His work was horrible. The lack of control joints was the most minor problem.

    @sprokitz: I insisted that he use wire mesh (which I already had on site for him) but I also know that he did NOT put it in because when I asked him he told me so, claiming it was unnecessary and overkill.

    The long stretch is abutted by the original driveway and house slab on one side and a new retaining wall on the other. In other words, the 80′ section buts against concrete the whole way down.

    Is there any chance that the long 80′ section won’t crack with no joints cut?

    The main thing I’d like to understand is: are control joints intended to stop shrinkage cracks from shrinkage that occurs during the initial cure? If so, why would they be useful at this stage, when it is 99% cured?

    virtually no chance the 80′ section will not crack. There are two kinds of concrete “Concrete that is cracked and concrete that will crack”

    Concrete continues to cure over months and continues to shrink over that time also. control joints do not stop cracks but try to give the concrete a weak place to crack in somewhat of a straight line instead on a crooked line. There is no guarantee that concrete will crack in the control joints but a greater chance it will crack there.

    My guess is that there are already hairline cracks that you can not see that will open up over time in the 80 foot slab. Concrete will shrink about 6 tenths of an inch per 100 feet on average, greater if the concrete is poured with a higher water cement ratio than .35 or .4 My guess from what you say about the contractor is that he probably poured at a much higher water cement ratio.

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