Moist Cure Duration 1

[jike]

ACI tells us to moist cure 5 days at 70 degrees F or 7 days at 50 degrees F for standard 28 day concrete. What about high early concrete that fully matures in say 7 days or 10 days? What duration of moist curing should be used? Any guidelines? Can I proportion the required cure times or is there some formula that I can use?

 

[Ron]

Generally high early strength concrete should be cured in the same manner as conventional concrete. The reasoning behind the minimum curing time for concrete is to allow it to achieve a minimal level of strength before you allow the autogenous curing/hydration process to prevail. Usually you look for 50 to 70 percent of f'c during the curing process. For high early strength, you can usually achieve that in about 3 days.

 

[jike]

Ron:

I am a little confused by your answer. The first sentence says to cure HE concrete the same as 28 day concrete but then the last sentence seems to say 3 days.

Which is it???

 

[Ron]

jike...what I meant by that is it should be cured under the same strength gain criteria...so if you wait until the normal concrete gains 70 percent strength, say at 7 days, you would cure the HE concrete until it reaches 70 percent, which will typically come in 3 to 4 days.

 

[jike]

Thanks Ron for the clarification!