When can I drive on new concrete? (1 Viewer)

[WarDamnEagle]

I think the real point is that it results in stronger concrete and it also reduces shrinkage cracks:

Allow Proper Time to Water Cure - Increase the Strength of Concrete Slabs - The Concrete Network

Six Ways to Minimize Concrete Cracking

www.concrete.org/General/f224R(01)Chap3.pdf

 

[RavenTai]

www.concrete.org/General/f224R(01)Chap3.pdf

3.4.5 Effect of curing on shrinkage—Carlson (1938) reported
that the duration of moist curing of concrete does not have
much effect on ultimate drying shrinkage. Test results from
the California Department of Transportation (1963) show
that substantially the same shrinkage occurred in concrete
that was moist-cured for 7, 14, and 28 days before drying
started. As far as the cracking tendency of the concrete is
concerned, prolonged moist curing may not be beneficial. A
general recommendation is to continue moist curing for at
least 7 days. (For further information, refer to ACI 309.)

good read, tomorro mornign will be 7 days, gleamed some good info for the next pour, the shop slab will bo much more critical.

 

[trainrech]

i've never heard that water slows the cure time. water assures that the chemical process in the concrete , isn't interupted because of lack of h2o.

The issue is evaporation and the rapid loss of free water that results in shrinkage and cracking of the concrete. Any water needed for hydration is added at the initial batching.

We maintain a minimum of 7 days wet cure and are doing experiments with 14 days wet cure for bridge decks. A little different situation though in that we have a helluva lot of rebar - typically a top mat and bottom mat with #5 and/or #6 bars on 6" centers each direction. There are no control joints and we are working to control cracking on single pours of up to 600'.

On most approach paving there are control joints cut at ~ 10' spacing. In lieu of a wet cure, we coat the surface with "cure", a white pigmented paraffin-based liquid.

As far as the question of strength and when to drive on it, I'd suggest 7 days as well. With a decent supplier, you may well see your 3000 PSI in that time frame.