Colored concrete has become popular among engineers and architects for such applications as sidewalks, driveways, floors, concrete products and other architectural uses. The ability to produce permanent color without adversely affecting other properties of concrete must be determined before coloring agents can be confidently and safely used. An investigation of limited scope was conducted in the Joint Research Laboratory of the National Sand and Gravel Association and National Ready Mixed Concrete Association at the University of Maryland. All concrete was proportioned, without adjustment for the pigments, to have a 3 to 4 inch slump, to contain 5 sacks of cement per cubic yard and no purposely entrained air. Each pigment was incorporated in the concrete at the manufacturer's recommended rate and then at twice that rate. Batches were designed to yield three 3 by 6 inch cylinders and four 3 by 4 by 16 inch prisms. The results were the pigments were found to be relatively inert when incorporated in concrete and were not detrimental to its more important qualities. Variations in mixing water requirements were small. Strength showed slight improvement when pigments were used, but the magnitude was probably of little practical importance. The colors were reasonable permanent even when the concrete was exposed to natural weathering.
Decorative & Concrete Surfaces
An Investigation of Fastness of Concrete Colors
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