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How long must concrete slab cure before anchoring equipment?

  1. Feb 13, 2015 #1
    We cut the concrete flooring in our plant for some plumbing work and will soon re-pour a slab of 5,000 PSI "High-early" concrete. In order to minimize down-time we need to re-install equipment by drilling/anchoring into new concrete as soon as the curing has yielded sufficient strength. The equipment would be anchored using 1/2"X3" stainless steel wedge anchors and weighs cca 500#'s. It rests on 4 3"x3" feet forming a cca 5' square. Will two days of curing allow for sufficient strength to drill and compress wedge anchors without causing the new concrete to break under the tension?
     
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  3. Feb 13, 2015 #2

    berkeman

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    Who is doing the pouring? It would seem that is a question for their managers and consulting engineers...
     
  4. Feb 13, 2015 #3
    You're not wrong in saying that's a question to be answered by managers and consulting engineers. Posing the question here is a little more handy at the moment.
     
  5. Feb 13, 2015 #4

    berkeman

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    But what if we give you bad advice, and the floor cracks? Who loses their job? :-)
     
  6. Feb 13, 2015 #5
    I'm not looking for anyone's stamped recommendation which I can bring to court to hold them liable; simply looking for a rough estimate and some generic advice based on experience.
     
  7. Feb 13, 2015 #6

    Bystander

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    Put it this way --- not even tract housing developers start bolting down mudsills at two days.
     
  8. Feb 13, 2015 #7
    Fair enough, but they don't leak $10K/hour during down-time.
     
  9. Feb 13, 2015 #8

    Bystander

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    :rolleyes:Depends on which set of books you audit.
     
  10. Feb 13, 2015 #9

    davenn

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    as Bystander said, depends on what side you sit

    consider how many $10's of 1000's its going to cost if the concrete is used too soon and the whole system fails and needs to be redone
    wasting even more time and materials that all = lots more money


    D
     
  11. Feb 14, 2015 #10
    Did you not have a timeline of work progression made at the outset? Especially with your downtime cost. How do you know you are on schedule and within your budget?
     
  12. Feb 14, 2015 #11

    Vanadium 50

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    You got that advice - ask the project engineers.

    It sounds like you are looking for a reason it's OK to use a shorter duration. I don't think you're going to find that.
     
  13. Feb 14, 2015 #12
    The people who sell the concrete should have a table that shows compressive strength verses cure time and importantly verses temperature. Time and temperature and moisture effect cure. Keep it warm and moist. The amount of money lost because of down time would pay for an engineer. To what extent, if any does the equipment vibrate?

    http://www.sakrete.com/uploads/downloads/Sakrete%20Fast%20Setting%20Concrete%20Mix%20TDS.pdf [Broken]
     
    Last edited by a moderator: May 7, 2017
  14. Feb 14, 2015 #13

    CWatters

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    Talk to the company supplying the concrete. Beware that wedge anchors don't seal the hole so if you wash the floor it's possible to get water sitting in the hole causing the anchor to corrode. Some people favour resin or cast in anchors for that reason.
     
  15. Feb 14, 2015 #14
    If you heat the poured concrete to 120 degrees F for one day you can get 75% of the ultimate strength. Keep it wet and make sure you don't exceed 180 degrees or this will cause unsound concrete at later dates. This is how precast manufactures increase production, they accelerate strength development with heating so that they can strip molds sooner to refill.
     
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