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White powder on concrete surface

by anonymous
(Oklahoma)

Q. We had about 640 yards of concrete poured and once it was all down and bullfloating started in drizzle and then rained until the next day. So there is rain spots in different areas and a white powder comes off when you walk on the surface.

We had a party and everyone's shoes was white underneath. What is this?

I want to stain the cement but don't want the shiny sealant. Will just staining take this away? How do I get rid of it?

A. The problem with the surface is called dusting. It's caused by high water-cement ratio on the surface when finishing. It's not a serious problem, but can be a nuisance. Acid staining will get rid of most of it once you wash the residue off. Another option is to just lightly grind it with a floor grinder. This will eliminate all of it.
There are matte finish sealers that will protect the floor without the shine. They will also make the floor much easier to clean.