Iron oxide pigments can be synthesized in a range of pure, intense colors and are ground to find powders toprovide high tinting strength.

Concrete Color: Pigments for Concrete, Integral Colors

Pigments are finely ground colored particles that, when blended into a concrete mixture, infuse the concrete with their shade. Humans have been using pigments since Paleolithic times, when pulverized minerals and charcoal were employed in cave paintings that have retained their vivid coloration for as many as 30,000 years. While today’s pigments contain some of the same mineral oxides and carbon black compounds our ancestors used, synthesized pigments have substantially replaced pigments refined from naturally occurring mineral deposits. The new processes have resulted in pigments that have greater tinting strength and are more consistent and economical to use.

Not just any pigment can be used in concrete. The alkaline chemistry of portland cement plus long-term exposure to sunlight and weather can cause all but the most inert colorants to fade. In addition, concrete colors have to be wettable so they can disperse readily throughout a concrete mixture. And pigments must not interfere with the workability or structural characteristics of concrete. ASTM C979 — Pigments for Integrally Colored Concrete summarizes these requirements and should be the basis for colored concrete specifications.