I would like to first start off by saying that we use and recommend Integrally Colored Concrete for our colored concrete jobs. After reading the article below, you will have a better understanding of just why it is that we do prefer Integral Colors them over Dry Shake Colors Hardeners.
Just what is, Integrally Colored Concrete? It is concrete that has been added with a integral coloring admixture that when added to the concrete gives it a uniform color throughout the entire concrete. These integral coloring admixtures are typically a blend of synthetic or natural iron-oxide pigments and surfactants (or wetting agents) that are mixed thoroughly into fresh concrete before placement to achieve uniform homogeneous color.
The biggest advantages of integral color are convenience and labor savings, says Bob Harris, president of The Decorative Concrete Institute. Because the integral color is mixed into the concrete, you can simply place and finish the concrete as usual. There’s no need to dust the color onto the surface and float it in during finishing, as is the case with dry-shake on hardeners.
Another positive factor is that integral color is permanent because it extends throughout the entire concrete slab. So even if the slab surface is accidentally chipped, scratched, or abraded, the color will remain, unlike with surface-applied treatments. In our climate in Southeastern Minnesota where we have snow, dry shake color hardeners are inevitably bound to be chipped somewhere in the slab by a snow blower or snowplow. And when this happens, the spot will become VERY noticeable as it will be a spot of gray in a otherwise sea of color. Manufacturers also say that the pigments in integral coloring admixtures are chemically stable and won’t have adverse reactions with each other.
The chief disadvantage of integral color is that the hues are more subtle and less intense then what you can achieve with color hardeners. In fact, iron oxide based integral colors are only produced in three basic hues: red, yellow, and black. Manufacturers concoct all the other shades, such as browns, tans, and mauves, by blending the basic hues in different ratios. The exceptions to that of course are blue and green tones, which are possible to produce but typically cost at least two to three time more than iron oxide pigments because different mineral oxides are used.
Dry Shake Color Hardeners
Most shake on color hardener manufacturers make blend pigments, portland cement, finely graded silica sand, and wetting agents. They come in powdered form, packaged in bags or pails, and are tossed or hand broadcast onto the fresh concrete. Thus the only color in the slab, is only on the surface.
Dry shake hardeners come in a wider array of hues than integral colors, including various shades of blue and green. As the name implies, color hardeners also densify the concrete surface because they contain hard mineral aggregates and portland cement. The result is a top surface that is denser than the lower body of the slab, but it needs to be so as the color won’t wear off.
You can mix in different colors to achieve contrast, using one shade as a base topped with as many as four or five different accent colors. By doing this technique on stamped concrete projects you can replicate the subtle color variations as you would see in natural stone.
Typically you are only able to use dry shake color hardeners on flatwork and not vertical items such as walls. These hardeners color only the top 1/8″ to 3/16″ of the slab. This makes them susceptible to wear and increases the chance that the original gray coloring of the cement powder will show through onto the surface.
In closing, Integrally colored concrete will have the same surface strength as standard concrete, but the color is permanent because it penetrates the entire slab. So even if surface abrasion occurs, the color will not wear away.
For all of our colored concrete projects, we use integral colors and of those most have a accent color (Release Color) applied to them so that the colors will reflect well off of one another. We can give recommendations as to which release colors work well with our Integral Colors, but as always feel free to come up with your own solution.
On your next concrete project, think about using color after all, at Gary Groh Construction, We See The World In Color! So should you!