How long must concrete slab cure before anchoring equipment?

AI Thread Summary
The discussion centers on the appropriate curing time for a 5,000 PSI "High-early" concrete slab before anchoring equipment weighing approximately 500 pounds. Participants emphasize the importance of consulting project engineers for specific guidance, as using the concrete too soon could lead to costly failures. While some suggest that two days may not provide sufficient strength, others point out that heating the concrete can accelerate strength development. It's noted that the concrete supplier may have specific data on compressive strength related to curing time and temperature. Ultimately, ensuring the concrete is adequately cured is crucial to avoid significant downtime and financial losses.
Dorin
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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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Dorin said:
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?

Who is doing the pouring? It would seem that is a question for their managers and consulting engineers...
 
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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.
 
Dorin said:
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.

But what if we give you bad advice, and the floor cracks? Who loses their job? :-)
 
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berkeman said:
But what if we give you bad advice, and the floor cracks? Who loses their job? :)

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.
 
Put it this way --- not even tract housing developers start bolting down mudsills at two days.
 
Bystander said:
Put it this way --- not even tract housing developers start bolting down mudsills at two days.

Fair enough, but they don't leak $10K/hour during down-time.
 
Dorin said:
they don't leak $10K/hour during down-time.
:rolleyes:Depends on which set of books you audit.
 
Dorin said:
Fair enough, but they don't leak $10K/hour during down-time.

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 moneyD
 
  • #10
Dorin said:
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
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?
 
  • #11
Dorin said:
simply looking for a rough estimate and some generic advice based on experience.

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.
 
  • #12
Dorin said:
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?

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
 
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  • #13
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.
 
  • #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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