The last time we wrote about integrally colored concrete, liquid dispensed color had just been introduced to ready-mix producers. Only a couple of manufacturers were involved in this market, but now most manufacturers of color for concrete have liquid dispensed products. It was thought at the time that dry powder products would phase out but that hasn't been the case. In fact, there are new markets for powder products and new forms of them available.
The market for integral color continues to increase. Some colors even reduce heat island effects and qualify for LEED points.
There are two ways to color fresh concrete: using integral or dry-shake hardeners (also referred to as “dust-on” or “color hardeners”). Dry-shakes are essentially a mixture of metallic oxide color, portland cement, and fine aggregate. They are broadcast over freshly struck off concrete and produce intense color finishes, higher strength and more abrasion-resistant concrete surfaces.
The benefits of integral
Integral color is made with metallic oxide pigments (which do not fade) and is batched into fresh concrete, dispensed in liquid or powder form. Specifiers like to use integral color on projects because batching can produce good color control load after load. By contrast, using dry-shake color hardeners depends on the skill of the workers broadcasting the color to achieve even thickness and uniform appearance. Contractors like integral color because they don't have to protect surrounding areas from color dust and fewer people are required for the placement. The timing of finishing steps is easier to manage too. Integral coloring can cost more though, especially as the thickness of placements increases. It's also more difficult or expensive to produce a lighter color than the color of the cement being used in the concrete.
The convenience of liquid makes this system particularly attractive to ready-mix producers and there is no mess. Another major advantage is that four or five basic colors can produce more than a thousand colors and hues, saving greatly on inventory and availability. Ready-mix producers install proprietary dispensing systems that are wired into the dispatchers' computer system. Software calculates the amount of color required based on the amount of cementitious material in a mix and the cubic yards of concrete for a load.
Owners of big-box commercial stores increasingly want colored floors. Almost all of this work is specified to use liquid dispensed color, greatly expanding the market. At locations where ready-mix producers don't have dispensing equipment to serve a job, manufacturers provide totes of the specified preblended color along with a dispensing unit to meter the proper amount into trucks.
Sales of liquid dispensed color also have increased through construction supply houses. To do this, color manufacturers install less expensive dispensing systems in supply houses so that contractors can buy small amounts for their projects. They tell their supplier how many cubic yards of concrete will be on a truck and the cementitious content. Their supplier meters the right amount of color into a bucket to color the load.
Liquid dispensed color includes water, so the additional weight makes it more expensive to transport. Also for some products, constant agitation is needed to keep solids in suspension.