new concrete problem

by dave
(san diego)

Q. Hi, 21 days ago I had a new concrete patio poured around my pool and then 3 days ago the pool plaster crew came in and plastered and dropped plaster on the new concrete and tried to clean it up with a wire brush, leaving large swipe marks across the new concrete. The concrete is standard grey with a light broom finish.

The contractor now wants to power-wash the entire new patio area thinking that the wire brushing took the top coat off the concrete to some degree allowing that area to release more moisture and is the reason for the difference in coloration. He thinks that by power-washing the whole patio the top coat will allow moisture thru and the coloring will all be the same. What do you think?

A. I think you will always have a slight discoloration in the wire brushed areas, even after power-washing the concrete. The wire brush did remove some of the paste at the surface, opening the pores and probably leaving a slightly scratched look.

If you want one even look to the concrete you can seal the concrete with a tinted concrete sealer. The concrete should be sealed anyway. Advanced Surfaces sells pigmented concrete sealers, they even have a concrete grey.