Find a Contractor
Or:
Colored Concrete Home
Concrete Color Charts
Ways to Color Concrete
Concrete stains
Integral Color
Dry-Shake Color Hardener
Concrete Dyes
Comparison Chart: Concrete Coloring Products
Design Ideas for Colored Concrete
Which Color Scheme is Right for Your Home?
Creating color and texture with Stamped Concrete
Adding Interest with Exposed Aggregate
Creating Excitement with Color: Endless Possibilities with Polymer Stain
Related Information:
Problems with colored concrete: Common problems, why they occur, and how to avoid or fix them
Colored Concrete Specs from Davis Colors: MSDS and tech safety sheets for tilt-ups, paving, cast-in-place, masonry, and precast
Guide to Buying Concrete Stains and Dyes
Lea este artículo en español

Section Sponsor

Colored Concrete

Question:

Last week, we poured a band of integrally colored black concrete. It looked great for three days, but then it rained a little the night of the third day, and by the next morning all the black color had disappeared, hidden by a grayish-white surface discoloration. What happened, and how do I fix this?

Deposits of efflorescence make black concrete look grayish-white.

Answer:

This is one of the most common but least understood phenomenons with concrete. Efflorescence is a chalky white salt residue that can occur with any product containing cement.

See our Complete Guide to Efflorescence

As moisture migrates up to the surface of the concrete, it carries along with it calcium salts from within the concrete. When the salts reach the surface, they react with CO2 in the air and form insoluble calcium carbonate. This white, dusty, scaly salt can be minimal or dramatic, depending on the amount of free calcium salt present in the concrete. Exposure to rain, standing water, and sprinklers only make the situation worse, as water triggers the reaction and creates more efflorescence.

Find contractors offering concrete cleaning near me.

Efflorescence is not as noticeable when it occurs on gray concrete, but even a little efflorescence on colored concrete can be a contractor's worst nightmare. Efflorescence makes red look pink, brown look tan, and black look gray or even white. The good news is that it will eventually go away on its own as the free calcium is depleted. The bad news is that this can take as long as 15 years. And in this situation, you can't wait.

To fix the problem at this point, clean the surface with a mild acid or efflorescence remover (some manufacturers make special efflorescence cleaners) followed by sealing. To avoid the problem altogether on future projects, consider using a colored curing compound or cure and seal to match the color of the concrete.

Shop for Related Products
Efflorescence Remover Concentrated cleaner. Safer than muriatic acid.
Industra-Seal 117 PLS Breathable densifier that protects from efflorescence.
Efflorescence Cleaner Water soluble formula safe for indoor use.

To learn more about efflorescence, read my other posts: Fixing Stamped Concrete and Fixing Colored Concrete

Find Concrete Cleaner & Sealers

Author Chris Sullivan, ConcreteNetwork.com technical expert and vice president of sales and marketing for ChemSystems Inc.