Until recently, concrete could only come in one color - dull and grey. Today, thanks to advanced technological developments, architects and designers can use concrete composition painted in any desired color when constructing structures. Modern paints and pigments for concrete are used to paint a wide variety of surfaces. In this article, we will consider the types of modern pigments for painting concrete surfaces, as well as the features of their use.
What is this?
Pigments for concrete are special powder additives, thanks to which you can give the desired color to the mortar or the finished concrete product. Such coloring matter after drying of the painted surface does not dissolve in water, oil and other liquids. In addition, provided they are of good quality, they are quite resistant toexposure to ultraviolet (sunlight) and leaching by rain. The pigment of each color has the ability to selectively reflect the flow of daylight. A dye of a particular color absorbs and reflects only strictly defined wavelengths of the visible spectrum.
There are only two exceptions: for example, a white pigment for concrete reflects almost the entire spectrum of color falling on it, but a black dye, on the contrary, absorbs most of the spectral waves.
Classification
Pigments used to color concrete are classified by origin into:
1. Organic pigments:
- yellow;
- scarlet;
- red;
- blue;
- green;
- purple;
- pink;
- burgundy;
- artificial cinnabar.
2. Mineral - inorganic powder pigments for concrete.
Natural:
- kaolin;
- iron minium;
-
manganese peroxide;
- chalk;
- graphite;
- lime;
- umber;
- ochre.
Artificial:
- chromium oxide;
- paint soot;
- zinc crowns and greens;
- burnt umber;
- dry lithopone;
- paint blue;
- zinc, titanium and lead white.
3. Metal:
- golden bronze;
- aluminum powder;
- zinc dust.
Toto obtain natural dry pigments for concrete, various natural materials are mechanically ground, and to obtain artificial dyes, mineral raw materials, such as ocher, are subjected to heat treatment.
Modern dyes are produced not only in the form of dry powders, but also in the form of emulsions, concentrated pastes and microcapsules.
Key Features
Depending on the chemical composition, the coloring pigment for concrete has characteristics such as corrosion and temperature resistance and color. The pigment composition has the following properties:
- Lightfastness - the dye will retain its original color or close to it under the influence of ultraviolet radiation. The most resistant to such exposure are natural pigments.
- Covering power - the ability of a pigment composition when applied to a surface to cover its color.
- Dispersity - depending on how finely the coloring pigment for concrete was ground. The finer the grinding and the finer the particles, the higher the coloring power and hiding power of the composition.
- Chemical resistance to alkalis - resistance of the pigment color to the alkaline environment of the cement slurry.
- Oil absorption, which refers to the ability of pigment particles to hold the required amount of binder composition (oil) on the surface. It depends on the origin and dispersion of pigments. The lower this indicator, the more durable and economical such a coating will be.
Coloring methods
Today there are twothe main method of coloring concrete structures. One of them is the coloring of the concrete solution during its mixing, and the second is the painting of ready-made structures from this material. Let's take a closer look at each of them.
Painting method at the stage of mixing solution
According to most experts, the most uniform color of a concrete structure is obtained when a dye, a pigment for concrete, is introduced into the composition during mixing of the mortar. Thanks to this, the concrete surface becomes evenly colored throughout its thickness and does not lose its attractive appearance as the top layer wears off. Color saturation directly depends on the amount of pigment introduced into the solution, the price of which is quite high, which determines the higher cost of colored concrete compared to traditional ones.
This staining method is used for monolithic pouring of various outdoor areas, creating decorative and retaining walls, producing curbs, paving slabs and paving stones.
To obtain a beautiful and "pure" color, it is best to use white cement and sand to prepare the mortar. To obtain the maximum effect, before introducing the pigment into the mixture, it is diluted in water to the consistency of "sour cream", mixed thoroughly and left for several hours - to brew. Then, stirring constantly, the resulting composition is poured into the solution and mixed thoroughly.
As already mentioned, today you can buy pigments not only in the form of dry mixes, but also concentrated pastes,microcapsules and emulsions, which allows you to add pigment for concrete with your own hands and create a solution of the desired color and in the required quantity.
Coloring finished concrete products
For monolithic concrete structures and prefabricated concrete products, this painting technique will be the most appropriate. A layer of a coloring composition is applied to the surface of already hardened structures, penetrating into the structure of the material to be painted by several millimeters. How deeply the dye penetrates directly depends on the carrier in which the pigment was dissolved.
Various varnishes, colorless bases for facade paints and other water repellents can be used as a pigment carrier. The deeper the carrier can penetrate deep into the concrete structure, the longer it will retain its color and attractiveness under the influence of ultraviolet light and adverse environmental conditions.
Can I make my own coloring pigments?
Industrially made dyes have a number of advantages over self-made ones, however, if you have the desire and perseverance, it is quite possible to create a pigment for concrete with your own hands. To create such a dye you need:
- water-soluble pigment for paints;
- water-based primer for mineral surfaces;
- water.
In the event that the primer is not concentrated, then 20 to 30% water is added to the mixture. To obtain colors that are closest to natural, natural,it is best to mix several pigments of the corresponding colors. It is important to remember that mixtures painted in this way, after drying, must be additionally treated with varnish, since they do not have protective properties. To ensure resistance to moisture and sunlight, such processing is carried out every 4-5 years.
