The color of concrete is affected by:
– used pigments and their quantity;
– used cement;
– aggregates (sand, crushed stone);
– curing mode.
Effect of pigments
A certain color can be obtained using pigments of different companies, but for reasons of economy, it is necessary to give preference to pigments with high coloring ability. It is often justified and more profitable to use expensive pigment due to its low dosage compared with cheap and low-quality pigments.
An important factor is the color stability of the pigment, so that the shade does not change from batch to batch, as is often the case with cheap pigments.
To get different shades, pigments are mixed with each other. Dark shades achieve the addition of black pigment, or the use of organic pigments (soot). All colors are selected individually by experience.
Cement has a great influence on the final color of concrete. The purest color is obtained on additive-free and white cements. The more cement-saturated the mixture, the more intense the color. In the production of concrete on gray cement, it is necessary to use a larger amount (3-5%) of pigments to achieve a consistent color. It is important to take into account that the color and quality of cement varies depending on the manufacturing plant, therefore, to ensure the consistency of the color of the products obtained, it is necessary to purchase cement at one plant.
Influence of placeholders
The color of sand and rubble does not affect the final color and color level of the concrete product (in the production of vibratory casting technology). The effect is caused by the degree of contamination of sand (the amount of dust and clay), especially when working with white cement.
The intensity of the color depends on the amount of water in the concrete mix (the less water, the stronger the intensity) and its hardness (the harder the water, the weaker the intensity).
The intensity of the color is higher, the lower the temperature of hardening of the product (at a high initial temperature, a flour shade may appear). Long standing in the forms increases the intensity.