Q: I am patching and repairing some existing concrete curbs and sidewalks that are a light sandy color. The quick-mix patching products tend to be dark gray, which does not match well at all. How can I get the repair concrete to be a better match?

A: This kind of patching is harder than you might think. One difficulty of color-matching patches is the fact that the existing concrete isn't just one color, and the variations become more obvious when you add a one-color patch. Here are some suggestions.

  • Get a commercial polymer patching product made with white portland cement, then add a little regular cement to deepen the color. Patching cements often look darker than the color of the cement alone because they contain polymer bonding agents that make the concrete denser.
  • Tint the patch mix with water-based, metallic oxide pigments for concrete, which are available at paint stores and construction supply houses. You can buy a full range of colors, including white. Colors that come in liquid form work especially well for this.
  • Add a light-colored pozzolan called metakaolin to your patch mix.
  • Keep trying and adjusting the mix until you find the right recipe.