Concrete Set-Up Time

Old 08-02-03, 03:24 PM
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Concrete Set-Up Time

I am pouring a 4' x 16' x 5" concrete slab... how much 'play time' will I have assuming it's 80 degrees and 75% humidity? By 'play time' I mean setting anchor bolts, skimming the top to level it, adding a little extra if needed, etc.

Old 08-02-03, 05:29 PM
Join Date: Aug 2000
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Perhaps the following sites will help you:

Time is of the essence when working with concrete. Helpers are important. I did a concrete foundation with two helpers. It was hard work for a little person. We worked fast.

I have read that the batch time is important. Check the ticket upon delivery. Between batch time and delivery less than an hour is preferred. Over 90 minutes, refuse the load. Pouring shouldn't take longer than 30 minutes.

If it's excessively hot, you will need to cover the concrete to prevent quick, excessive evaporation. Without the proper care, concrete may have reduced strength and will be very prone to cracking due to rapid drying. It may stiffen quickly and make finishing difficult. Between 75F. and 100F., temperature tends to result in concrete problems. Low relative humidity and high wind tend to cause the most problems, especially on hot sunny days. Keep subgrade and forms moist before concrete truck arrives. The simplest way to control problems is to keep the concrete cool by keeping it sprinkled and letting the evaporation process cool the concrete.

Your concrete should be kept moist for about 7 days after the pour. Moist curing concrete will be up to 50% stronger then dry cured. In about 30 days your concrete will reach its maximum hardness. For best results wait 8 hrs for the face to cure then dampen with a hose.

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