Concrete White And Dark Patches

Stone_Mason

Hi thanks for taking the time to read this i am a stone mason by trade i specalize in granite and marble i made benchtop and vanities and also headstones. But now for the last 2 years have been installing and reparing headstones or if you are in the usa gravestones. So i have had to teach myself concrete and plastering which i think looks good. I work for a boss and there is one other person there. The question is i do a lot of concreting and i have notice that the concrete that i have poured after a month or so is white in some areas and dark in others so it is quite patchy is this because of not enough cement or is taking longer to dry because it is quite deep about 10 inches. If anyone knows that would be great also the concrete was mixed in a mixer thanks for your time.

Stone_Mason

Hi i have uploaded a photo of the concrete to my album if you want to see what i mean thanks.

genecarp

WHAT color portland are you using?

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genecarp

how did you finish the surface? by hand, or some type of form?

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Stone_Mason

Hi it was grey portland cement and finished with a steel float.

genecarp

Stone, what is your climate (during the pour?) is the effect on the verticle surfaces, or only the horizontal? Did you cover the pour after finishing? Welcome to CT, what country are you in? G

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Stone_Mason

Hi the walls were plastered so all i can say is the top panel the weather was mild and it wasnt covered i went back the next day and watered it with the hose. Thanks for the wellcome.

Stone_Mason

Location is the North Island of New Zealand.

genecarp

Is there any difference in the texture from the dark to the light? when you hosed it down, is it possible you removed some of the cream from various spots, exposing more aggregate and causing a color change?

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Stone_Mason

Hi the surface is the same and no it hadnt washed of the top coat its just light in some areas and dark in other as in the photo thanks.

Blackhammer

I have the samething happen to my concrete. None of mine is hand mixed all ordered out of a truck. It looks normal to me. Concrete never stops curing. Majority of the curing process takes place in the first 28 days, this is why they crush the final cylinder in a psi test on the 28th day. This being said I think the finish looks good it just needs more time to bleachout to the nice light grey you are used to. I have had slabs with cure and seal on them take 4+ months to bleach out.

Stone_Mason

Thanks Blackhammer for the info it is amazing the art and science behind concrete it gets taken for granted.

Stevelsc8721

I had the same with transit mix on a driveway, we did two driveways side by side. Called the mix company and they said the sun will bleach it out?

It took almost two years and visits to court to finally get paid. I now have a new clause in my contract about color and blotches

Stone_Mason

Hi steve did they every find the cause of the blotches and did they go away and if so how long did it take thanks

patron

would you mind sharing the verbage in regards to the color and blothes? i rececntly added a concrete is garanteed to crack clause to my contracts. this would round out the package for me.

dprimc

Love the guaranteed to crack clause....only two types of concrete; cracked and going to crack.

patron

no joke. picked that up from other contractors. then again i usually do tell potential customers at estimates that concrete will crack but we do all we can to make them crack where we want it too. tho we all know concrete does what it wants.

blast4cash

I used to run a ready mix plant I would only guarentee 3 things. It will come in a big truck it will get hard and it will crack.

TERM101

Ive notice that sometimes inconsistent floating/troweling in some spots versus other spots will cause different water concentrations in certain spots and cause these white splotches. Also covering concrete with anything will sometimes trap the bleed water and allow it to just set under whatever is covering it, this sometimes causes light areas.

beretta13

Slag