A new liquid pigment dispensing system removes human error from the coloring of ready-mix concrete, developers note, and results in more consistent shades, faster mixer truck cycling, the elimination of botched colors, and happier drivers. Producers who have installed the system find the resulting faster truck cycling has paid for the equipment within months, with the tighter control over shading providing better profit when selling value-added color concrete mixes. They have also found that the system's computer documentation capability is helpful in duplicating shades and resolving potential disputes on color variations.

The ease and consistency of supplying colored concrete is helping a Colorado ready-mix producer extend its presence in an established decorative-flatwork market. "It's a quicker process and we can treat color orders no differently than gray concrete," says John Ruppert, sales manager at Colorado Springs' Transit Mix Concrete Co. "It doesn't require as much attention on the part of the driver, and the mixing is more uniform. In the past, we've had 'ribboning' of color down the chute due to hang-up of dry powder on drum fins. That element is removed."

Faster cycle times The conventional process of adding color to ready-mix typically requires pulling a loaded mixer out; locating the right color bags and carrying them back to the truck; climbing up on the truck and dumping the contents of the bag into the truck without the driver spilling it on himself or anywhere else. Producers report that this sequence can take 15 to 20 minutes.

The resulting faster turn-around or cycling of mixers has more than paid for the liquid dispensing system in a matter of months, according to one of southern California's major ready-mix players, Standard Concrete Products Inc., Santa Ana.

Standard Concrete's dispensing system was installed in January 1999. "It's paid for itself already," says Rich Gibson, vice president of operations. "And it doesn't have anything to do with the cost of the color. Instead, the savings comes from the labor factor. If I only look at the amount of time saved by drivers, that 15 to 20 minutes per load from January through September has more than paid for the system."

The time savings also results in better equipment utilization. "In the past, if we were pouring a hundred yards of colored product for a shopping center, I'd have to put five trucks on the job and round-trip them at least twice," Gibson explains. "Now I can do that same job with three or four trucks, because there is no delay in the loading process."

Also, drivers seemed to have their own thoughts on dry colors. "My guys disliked the dust flying in their faces, the task of climbing up and down the ladder, and the dry color sticking to their faces and clothes all day," Gibson says. "They had to do it, but would grumble about it. Now the guys don't care because the system doesn't create problems."

Another headache eliminated is the potential of driver error in obtaining the right number of the correct sacks of dry color from the plant warehouse. "The sack on top of the pile might have been the right sack, but because inventory had been moved around, the sacks underneath may not have been the same type," Gibson says. "But the driver might have made the assumption that they were, and we wind up with the wrong color. Perhaps two or three times a year we would have to take out concrete of the wrong color." That could cost anywhere from $2,500 to $5,000 per mistake, he adds.

Yet another advantage is a much smaller color pigment inventory, and the elimination of discrepancies between different lots of the same dry color in a plant's inventory. "Storage and dispensing totes are our inventory," Gibson notes.

Also, if a unique color is desired, the shade can be batched immediately, instead of having to separately procure or special order it. "This eliminates the two or three-day delay from when the customer wanted to pour the concrete," he says. "The customer gets better service."

Liquid color process The SGS Color Select System in use at Standard Concrete and Transit Mix was introduced by Springfield, Ill.-based Solomon Colors at World of Concrete in January 1999. Approximately 15 systems had been installed by October, and Solomon is projecting a tenfold increase in installations next year.

>From four primary liquid iron oxide pigments, hundreds of standard or custom color blends can be created using a programmable logic controller (PLC). In its basic form, the system is composed of four, 3,950-lb. liquid color "totes" arranged on a rack; a control panel; hose pumps; and a weigh-cell holding chamber. A plant operator inputs the color parameters via the control panel, and the onboard PLC starts each pump for the required colors, weighing components into the weigh chamber. The system alerts the operator when the fill cycle is completed, and waits for a prompt before thoroughly discharging the pigment into the mixer via air and flush water.

"One of the benefits of the metering system for the ready-mix industry is accurate batch control," says Richard Solomon, president of Solomon Colors. "With four basic colors the producer can create any shade without having to stock 20 or more different colors. A custom color can be developed on the spot."

Those four basic colors are yellow, two shades of red, and black. "With those, you can create any shade you want, with the exception of green and blue," Solomon notes.

Imparting value In a world of gray mix sold as a commodity, the ability to add value to a load of concrete is a significant plus for the profitability of a ready-mix producer. "Value-added color mixes contribute significantly to our bottom line," Gibson affirms. In addition to the four basic colors, he notes, Standard Concrete is using a fifth tote for black liquid pigments.

"We use the color system for everything from backyard patios and driveways, outdoor spas, and all the flatwork around a house," Gibson says. With affluent cities such as Newport Beach, and celebrities building extravagant homes elsewhere in Los Angeles, he adds, the company is fortunate to have such a market.

Standard is providing color concrete for Disneyland's expansion in Orange County and at new shopping centers, which are changing to outdoor layouts. "They aren't building enclosed shopping malls these days, as much as developing an open shopping area of retail units and plazas," Gibson says. "The public areas are being dressed up with different concrete colors, or different colors side-by-side." Also, color concretes are being specified for municipal work, such as ADA curb cuts, which are colored dark for easy identification.

Economy spurs color growth Colorado's Transit Mix is seeing the market for color concrete grow year after year. "The economy is so good that it's created a lot of business for us," John Ruppert told Concrete Products. "We do all we can to make customers happy and help them be more creative in building."

To build product acceptance, Transit Mix staff interfaces frequently with concrete contractors. "We use color capability as a sales feature," Ruppert says. "I've had several finishers notice that mixes are more consistent and uniform."

Transit Mix uses black, yellow and two red pigments. All color orders are dispatched from a central Colorado Springs plant. The liquid system replaces conventional dry products which, Ruppert notes, were less functional.

In the old process, the batch operator would weigh the required dry color and leave it on the loading dock for the driver, eliminating one potential pitfall. "But if you've got multiple color orders, there still could be confusion. This liquid color system takes the driver out of the equation," Ruppert says. Environmentally speaking, the liquid pigment eliminates stray dust from being discharged to the atmosphere, he adds.

Solomon Colors reports that it has manufactured inorganic iron oxide pigments for the masonry and concrete industry for over 50 years. Its product line includes dry powder and liquid colors, dry-shake colored hardeners and colored release agents.

Introduced earlier this year, the SGS Color Select liquid color dispensing system permits blending of one to four colors in a single batch, at a rate of 1 to 7 percent pigment. The system utilizes hose pumps, which can be operated in the forward or reverse direction. The reversing feature operates only in manual mode, and can return unused product to its storage container after a production run or maintenance operations.

The controller starts the pumps after receipt of a fill signal. The signal can be used remotely by plant process equipment or by pressing the manual start button on the face of the control panel.

A "fill completed" signal is issued upon completion of the timed cycle. The system utilizes a holding chamber over the mixer that collects the material from the four pumps and holds it until it is requested by a discharge signal. A flush cycle follows and ensures that all material has been added.

New twists for the next SGS generation will include a PC to interface with many existing controls, Solomon officials note. Larger storage tanks for color will also be available for high-volume users.