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Stamped Concrete - not happy

Posted by pm92508 SoCAL (My Page) on
Tue, Aug 7, 12 at 17:00

Could someone comment on the attached pictures? To save water and maintenance, hired contracter and replaced grass with stamped concrete. Now that everything is done, somehow I am not convinced with the result for the following reasons -
1) The resulting concrete looks too bright. Initially I decided to not to add any color so that it will match the existing concrete (other than the release which was little dark grey to give it shades). Once done, I was expecting power wash (per my googled knowledge) but contractor says that will remove the color release from the concrete. He is suggesting sealing it after a month in order to see the shades.
2) My backyard is on west so too much reflection. Can't think of sealing it and cause more reflection.
3) There is color residue on the concrete from the release color (which was supposed to be dark grey?). My feet get white when I walk on the concrete. Contractor says it will be there until I seal the concrete.

any suggestions, fixes, recolor options? I am leaning towards power wash to get rid of that white residue. Please advice.


Follow-Up Postings:

RE: Stamped Concrete - not happy

The white powder that is rising to the top of your concrete is a natural process that varies from concrete batch to batch. It is calcium carbonate , a type of efflorescence.

It's a chemical process and is easiest to understand the various reasons why this happens if you simply google the key words concrete efflorescence or calcium carbonate / concrete. It occurs under a variety of reasons.

Your contractor is right, by power washing a topical applied coloring agent (your color release ) you will blow out your coloring agent.

There are sealers that are not shiny. They are called penetrating sealers. You'll want to wait till the concrete is fully cured before applying, especially if you are experiencing a lot of efflorescening - it can trap the migrating calcium in the porous concrete and can create a lot of color variation .

You can use a soft to medium brush to removed that calcium.
Depending on the wet mix, it will continue for a while .. or not. Concrete is a tricky beast.

I hesitant to recommend a remedy because I do not know the full scope of the pour, your climate, the mix and the type of admix ( if any ) and the type of colorant.

Best to take the recommendation of your contractor if you feel he is a seasoned professional.

RE: Stamped Concrete - not happy


Thanks for the reply. I also poured the concrete at my vegetable garden patch area at the same time. Now, this was not stamped and it looks great and no efflorescence or so. This is the peak of summer and the daytime temperature this week is varying between 100 to 107 degrees outside.

Also, thanks for the info on non-shiny sealers.

RE: Stamped Concrete - not happy

One 'possible' reasons why you may not be having the efflorescence in the veggie area is that the sub base or the soil base was really really dry when the same batch of concrete was poured.

Temperature of sub base , sub base moisture content and the type of sub base are just a few elements that are taken into account when doing 'exploratory recognisance'.

Maybe ( just throwing out a thought ) the veggie area subbase was warmer , dryer and the time of the pouring the air was dryer.

Like I said, concrete is a beast. .. a beast that can be very difficult to control and at most times difficult to predict exactly.
That's one of the reasons that there is so much fine print in a concrete contractors contract ! :-)

RE: Stamped Concrete - not happy

We get that efflorescence every winter when it rains. Looks like snow on the patio and pool surround. We try sealing it, but it's hard to do vertical concrete because the sealer needs to sit a while.

It isn't easy to get off that white stuff either. I use a wire brush and then a broom.

I was told it happens because there isn't enough concrete in the mix. Too much sand/gravel. Concrete is expensive, and many contractors cut corners. Next time we have concrete poured, I'll gladly pay extra for the correct mix.

Good luck!

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