Iron oxide pigments are inorganic colorants used to color concrete, available in red, yellow, and black, as well as other shades like green and brown. They are durable, lightfast, and alkali-resistant, and they do not affect the strength of concrete when used at standard dosages. To use them, mix the powdered pigment with dry ingredients or the liquid with the water before adding to the concrete mix to ensure even distribution and color.
Key characteristics and benefits
Durable and lightfast: Iron oxide pigments are resistant to fading, bleeding, and weathering, ensuring the color lasts over time.
Alkali resistant: They are chemically stable in the alkaline environment of concrete.
Disperse evenly: Due to their small particle size, they disperse uniformly within the concrete matrix for a consistent color.
Non-toxic: These pigments are generally considered safe to handle.
Value-added: Adding color can make concrete more attractive and can provide properties like solar reflectiveness.
How to use
For powdered pigments: Mix the pigment thoroughly with the dry concrete ingredients (cement, sand, and aggregate) before adding water. This ensures the pigment is evenly distributed throughout the mix.
For paste or liquid pigments: Mix the liquid with the water before adding it to the other ingredients to help with dispersion. Some products come in dissolvable packets that can be thrown directly into the mix.
Dosage: The amount of pigment used determines the final color’s shade. Using more pigment results in a darker color. You may want to go a bit darker than your target color, as the color will lighten when dry.
Mixing: It is important to follow the recommended mixing time to ensure the color is fully incorporated into the concrete.
Important considerations
Consistency: Use cement from the same batch and measure pigment based on the weight of the cement, not the total weight of the concrete, for consistent results.
Safety: Wear gloves when handling pigments, as they can stain your hands.
Molds: If using pigments in molds, be aware that the color can transfer to subsequent pours if you use a latex mold. It’s best to use separate molds for colored and regular concrete
