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Coloring Decorative Concrete
March 7, 2017
How liquid colorants can provide even dispersal for a consistent, natural look.
Decorative concrete, which provides aesthetic value to concrete surfaces, is becoming increasingly popular. It can be made to look like any type of stone product, from flagstone to slate to bricks. Decorative concrete is also considerably less expensive to install than the materials it replaces, and it requires less maintenance and upkeep. Because decorative concrete mimics natural products, it requires colorants to achieve that natural look. In the past, this was done using dry pigments, which were mixed into the concrete or sprinkled on top as a surface treatment. Today, however, the trend is moving toward using liquid colorants.
Provides color throughout the concrete
Liquid colorants provide integral color, meaning that the color extends throughout the entire matrix of the concrete, not merely at the surface level, so if the concrete is chipped or scratched, any damage reveals the same integral color underneath. With surface colorants, if the top layer is chipped away, it would reveal gray underneath, because the color is only on the surface.
Dry pigments are a less expensive way to color concrete, but the length of the mixing time of the concrete can affect the color. The longer colored concrete is mixed, the more the dry pigment is dispersed, and the stronger the color becomes. Take, for example, a large job that requires multiple loads of concrete transported to the job site 20 minutes away. If traffic is heavy or there is a delay at the job site and it takes 40 minutes to pour the concrete, the additional time from when the color was added until when the concrete is poured will give the pigment additional time to disperse. As a result, the color will be stronger than originally specified by the architect. With liquid colorants, the pigments are already fully dispersed, making the color more consistent lot to lot than it would be using dry pigments. The concrete’s innate color can affect the final color, as well, but those color variations can be minimized by completing the entire job at one time. Liquid colorants also are less messy to handle, easier to store and blend faster than dry pigments.
Using a blend to achieve best results
The best result comes from using a combination of liquid colorants and dry pigments for the most natural-looking surface. Ideally, the liquid colorants are used to integrally color the concrete to provide consistent color throughout, then a dry pigment is spread on the surface to provide a different color to mimic stone and its natural variations. Blended liquid colorants can be added by residential contractors on site to ensure the entire job looks unified and doesn’t result in blocks of different colors in large, noticeable patches, particularly with items such as large commercial patio areas. The result is a more satisfied customer.For industrial colors, make sure the supplier has a palette wide enough to cover the requests of most clients. The palette should include earth tones for most applications, including several types of grays for a flagstone look, reds for a brick paver look and some terra cotta shades or tans for a sandstone look. Do-it-yourselfers also can use liquid colorants on their projects by adding small bottles of premixed colorants and water to a bag of cement to achieve integral color. These color packs are sold through most hardware stores.