# Concrete Curing Different Color



## rjschwar (Nov 13, 2009)

We had some concrete work done last week (4/22). The day they did it they brushed the finish just as it was starting to rain. They then put a tarp over the area (not touching the concrete). The next day they came back and were reworking some of the area (wetting and trowling) and they brushed it again. Now the slab is different colors. The contractor says it is still curing and it should all match up once it is all done, but I was wanting some impartial advice. Is it typical for this to happen. Portions are very light almost white while some areas are dark as if it hasn't dried. It feels solid but the colors are all different over the slab (maybe 6'x 8' area). Also if it matters they just used a bunch of Quickrete bags. It has improved slightly, but can I ever expect that the color will totally match. IT seems like it should be fairly uniform by this point. Last week we had a some rain but the last few days have been very dry and warm.

Thanks,

Richard


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## Bondo (Dec 8, 2007)

Ayuh,.... Concrete takes a minimum of 28 days to cure,...

Give it a month or two,...


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## rjschwar (Nov 13, 2009)

Great, good to know.

Thanks,


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## joed (Mar 13, 2005)

I'm more concerned about coming back the next day to trowel part it. Concrete should have setup in 2-4 hours and been untrowelable the next day. Next day to me would be 8-12 hours and no way should concrete still able to be trowelled at that time.


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## rjschwar (Nov 13, 2009)

They were scraping having to really go at it and adding water. I think the tarp had been dripping on one corner and they were drying to even it out. It looks OK besides the color. Will this have longer term impacts?


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## jomama45 (Nov 13, 2008)

As joed stated, it shouldn't be workable by any stretch of the mind the following day. Also, I hope you're in a warm climate if they used Quikcrete. I'd never suggest using it outside in a freeze-thaw climate.........


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## rjschwar (Nov 13, 2009)

We live in Seattle so don't get much freeze-thaw. Not sure why they were able to work it the next morning but where they were working on it it looks fine. Like I said it was pretty solid but just the very surface were they able to scrape around.


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## Bondo (Dec 8, 2007)

jomama45 said:


> As joed stated,* it shouldn't be workable by any stretch of the mind the following day.* Also, I hope you're in a warm climate if they used Quikcrete. I'd never suggest using it outside in a freeze-thaw climate.........


Ayuh,.... I ain't no Mud Expert by any stretch of my imagination, But,....

Many moons ago, We poured a pretty big retainin' wall up in Old Forge Ny with simons forms,...
A house, built back into the mountain,...
8' high at the garage door, out to 12' high at the "Road/ driveway", over maybe a 40' run,......
'n droppin' grade,... 5'/ 6' drop,...

The Owner wanted a _Round_ retainin' wall, so We poured on loose lockin' pins, 'n formed the simons form in a radius,... 
30'/ 35' if I remember,...

Next mornin' after the pour the afternoon before, We pulled down all the forms, 'n loaded 'em out,...
Lost 1 smaller one down inside middle of the radius, under the overhangin' rock,...
As I was helpin' the tear-down crew, Our Master Mason was scrubbin' the 'ell outa the face of the wall,...
He had a scrubbin' block, 'n made a paste outa cement,...
The concrete was Plenty "Green", as you could sorta easily dig it out with a framin' hammer,..
Anyways,...
It looked as "_Round_" as could be, you'd never know it was poured with 2' forms,...
No seams, No lines, just _Round_,...
Even it's Top, outside to inside,... _Round_,...

That's gotta been close to 35 years ago, 'n it's still there, still got it's face, 'n still _Round_,.... :thumbup:


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## stadry (Jun 20, 2009)

considering 1 can't get the same color out of 2 successive plant mixes due to sand moisture, where the cement is in the silo, how long in the truck, placing conditions, yada, yada, yada, not surprising your situation developed,,, plastic sheeting will cause a difference in color.

as far as curing time, no one knows,,, we do test at 12 & 24 hrs, 7 & 28days - if conc meets its design strength in a determinable time, we say its 'cured',,, however, normally conc keeps curing many times reaching strengths in excess of 25% more 

no one's ever come back the next day & troweled successfully,,, 1 might 'rub out' & 'dress' as bondo posted, tho


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