White Concrete:
Using white cement in your mix will allow you to achieve pure, consistent color, batch after batch. White cement also allows for more vibrant colors and reflects twice as much light as gray concrete, which may greatly lower your lighting costs.
by Loretta Hall
in the United States is gray. The other 1 percent is a startlingly bright white color. Because it represents such a small share of the market, many contractors know little about white cement concrete.
Portland cement's ordinary gray color comes from iron oxide and, to a much lesser degree, manganese oxide. These metals are usually present in the limestone, clays, and gypsum used to make the cement, and iron is typically added as a flux during the manufacturing process. To eliminate the gray color, manufacturers select raw materials that are naturally low in iron and manganese, and they process the materials without adding iron. These steps keep the iron content below 1/2 percent rather than the 3 percent to 6 percent typically found in gray cement.
White cement concrete has basically the same physical properties as gray concrete, so the color difference is the most obvious reason for using the white product. In its pure form, it provides a striking contrast with its surroundings. Coloring it can produce soft pastels or bright blue colors that cannot be achieved with gray concrete.
"I often use a white cement overlay because you can get really vibrant colors with it," says Levi Susoev, owner of River Alloy Designs in Kerman, Calif. Susoev showcased his techniques at the Artistry in Decorative Concrete demo at World of Concrete this January. He created a Mardi Gras mask design featuring iridescent blue, soft pinks and yellows, and transparent gray colors.
"Consistency is one of the biggest reasons that you would want to use it," says Larry Rowland, manager of marketing and technical services for Lehigh Cement Company in Allentown, Pa. The quality of gray cement is carefully controlled for performance characteristics, but not for color, which can vary significantly. When white cement is made, the color is also carefully monitored. "People will even utilize white cement to make a gray product," Rowland says. "They could make that gray product with gray cement, but when they have to go and match it six months from now or a year from now, it may not match."
Besides its visual appeal, white concrete reflects twice as much light as gray concrete. "We use a significant amount for full-thickness concrete floors we install for a large, regional supermarket chain," says Curt Meidling, operations manager for Meidling Concrete Inc. of Spokane, Wash. Along with the white floors, the stores have many skylights. The increased brightness allows the owners to cut their lighting costs significantly. "Those benefits are outweighing the added initial cost," Meidling says.
The main disadvantage is that white cement is more expensive than gray. Jamie Farny, program manager for masonry and special products for the Portland Cement Association, offers several reasons.
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