Both aggregates and cement may determine the final color of the concrete. For not risking altering the color pattern, it is interesting to maintain the same material suppliers during the execution of the work.

What influences the concrete’s final color?

Many are the factors that may influence the final color of the concrete colored with pigments. The main factors are the following:

Aggregates

For preventing the color of the concrete from being influenced by the color of the aggregates, it is important to keep the granulometry stable and use the same kind of aggregate during the execution of the work. The influence tends to be stronger on yellow and green than on darker shades such as red, brown and black.

Pigment

IIt is important to establish a saturation rate when preparing colored concrete. If increasing amounts of pigments are added to a  concrete mixture, the color intensity becomes stronger linearly at first. However, as more pigment is added, one does not manage to intensify the shade even more.

NOTE: When exceeding the saturation limit, pigment is wasted and there is also the possibility of a negative effect on the concrete’s technical properties.

Cement

White cement ensures lively colors to the colored concrete. Gray cement makes the colors more opaque. This loss of shine with the use of gray cement is not a standard for all pigments: it has greater influence on lighter shades, such as yellow and green.

Attention! The gray cement shade may also vary, therefore is important to maintain the same supplier during the whole accomplishment of the work.  Please remember that titanium dioxide does not replace white cement in the search for cleaner and brighter shades.

Water

When used in excess, water evaporates from the concrete, leaving cavities that resemble thin pores, which disperse the incident light and, therefore, make it lighter. Such dispersion does not depend on the pigmentation, for this also occurs with gray concrete.

Efflorescence

Efflorescence appears after a number of weeks of concrete exposure to bad weather conditions. Water dissolves  the free whitewash that is part of the hydrated cement and leads it to the concrete’s surface. After the water evaporates, a deposit of soluble salts white powder remains. Such salts are gradually washed away by rain. However, it is also possible to remove efflorescence using  a soft-bristle high-pressure washer or with an efflorescence remover found on the market.

Note that the pigments used for coloring the concrete do not influence the development of efflorescence.