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Thread: Question on shotcrete curing time

  1. Back To Top    #1

    Question on shotcrete curing time

    I am deep in talks with a builder who uses shotcrete.

    They told me they only need to let the shotcrete cure for 48 hours after it is shot, before working with it again.

    A gunite builder told me that you need to let it sit untouched for 30 days before working with it again.

    Can anyone give me some perspective on which is right here?


  2. Back To Top    #2

    Join Date
    Feb 2012
    Tucson Arizona

    Re: Question on shotcrete curing time

    I am no expert on concrete, but I think the answer is they are both right. Concrete is always curing and getting stronger, though that curve is logarithmic and the concrete is considered 'cured' after 30 days.

    The pool builder is also correct and that after a few days (assuming you have moistened it correctly) of curing, the pool building process can proceed.

  3. Back To Top    #3

    Join Date
    Feb 2012
    Central Indiana

    Re: Question on shotcrete curing time

    Yes both in a sense, Shotcrete and Gunite are both terms used to describe pneumatically applied concrete. Gunite used to mean just the dry mix method IIRC, where as shotcrete can mean either. So clarification on both their parts would have been nice. When using either method if done properly a couple days should be fine, the reason the dry mix method is used in structural concrete repair alot of times is the control over the moisture level can allow them to "hang" more material at a time. The reason for concrete being considered "cured" at 28 or 30 days is that at that point it has reached about 95% of its maximum strength. In certain cases however it can take longer if special coatings and sealers are applied this however is usually reserved for special applications. Typically the longer it takes to cure the more structurally sound it is. Wet cured Concrete (concrete kept wet during the cure)is usually significantly stronger than air cured though, or the more moisture it starts with the longer the cure the more strength. Temperature also accounts for a large part of this. Seeing as how your in NJ I assume, strength gain in colder temps is much slower 40degree concrete will be 35-38% of its design strength in seven days as compared to 70-5% for 73degree concrete.

    Too many variables to properly answer your question, they both could be right but i would find out more. it sounds like the guy with the longer cure time just might know his concrete a little better though. I would opt for quality any day.

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