Factors influencing the coloring of
architectural concrete

Figure: El Ahwany

Many different pigment shades are available to designers. These shades can be mixed and batched in various ratios to adjust them to the intended effect

Figure: El Ahwany

Varying effects can be achieved depending on the amount of pigment added to the concrete. Yet there is an end to it at 8% of the cement ratio – no significant increase in color intensity will occur above this threshold

Figure: El Ahwany

The inherent color of the cement may vary enormously; it influences the color of the concrete

Figure: El Ahwany

White cement can be used to achieve a more brilliant appearance of one and the same shade (in this case, ochre) whilst adding the same amount of pigment (4 % of the cement)

Figure: El Ahwany

The influence of the release agent is often underestimated. In this case, the same concrete and the same (non-absorbent) formwork were used. Even the weather conditions were identical. The color variations are exclusively due to the different release agents used

Figure: El Ahwany

Concrete is actually grey, but it can be colored. Yet many aspects need to be considered to achieve the intended
result.

This article deals with the most important aspects whilst particularly focusing on the production of precast elements and cast stone items.

Pigments

Pigments (powders, granules, beads or liquid paint) are used for the coloring of concrete (Fig. 1). For this purpose, the required amount of pigment is calculated relative to the cement. Pigments usually account for about 2 to 8 % of the cement contained in the concrete. Color intensity initially increases in line with the amount of pigment, but stagnates once a certain percentage has been reached (Fig. 2). Colors are often mixed to create the...