Producers are forced to constantly improve the competitiveness of their products due to today's market saturation with imported and Russian materials. Therefore, along with quality properties, decorative requirements are also imposed on products.
Definition
Iron oxide pigments are an inorganic type of substances, consisting of oxide hydrates and oxides of different valency levels. According to the method of obtaining, they are divided into natural and synthetic. Compared to natural, the latter are used much more often. This is justified by the high content of dyes in synthetic pigments and low cost. Iron oxides have a wide range of colors, from black and blue to yellow and green tones.
Iron oxide pigments: characteristics
Among the properties of pigments, it is worth noting the following:
- Coverage reflects the expense to cover a unit of plane. The lower this indicator, the less substance will be spent.
- Dispersion. Withreducing the fineness of grinding increases the coloring ability.
- Intensity is the ability to convey its hue when mixed with other substances of a certain saturation. The intensity is displayed as a percentage of the manufacturer's standard.
- Light fastness is the resistance to photochemical attack.
- Permanence. Regardless of the batch, the hue should not change intensity.
- Heat resistance is the ability to retain color within a specified temperature range.
- Availability of water soluble additives.
- Acidity of aqueous suspension. It should not exceed the optimum pH=7. Due to the fact that the cement is alkaline, the use of a low acidity agent will completely discolor the mixture.
Concrete coloring
For painting concrete products, iron oxide pigments have been used for a long time, which have low hiding power and a distinctive coloring characteristic. They are not affected by alkali, some types of acids, s alt, sunlight. Due to this, pigments have become so common in the coloring of cement hydration objects.
The stores offer iron oxide pigments of foreign and Russian production. To give concrete a shade, depending on the region of manufacture, the introduction of substances from 3 to 15% of the total weight is required. It should be borne in mind that pigments have a greater dispersion in comparison with Portland cement,therefore, if the specified concentration is exceeded, there will be a sharp increase in the need for the mixture in water, which will subsequently lead to a significant decrease in strength during pouring and an increase in porosity.
Iron oxide pigment: application
The technical data of the equipment affects the efficiency of the use of dyes. With a small proportion of pigment in the bulk, to obtain complete dissolution, equipment is required that has a high mixing speed. The pigment changes the color of only the cement binder of the entire concrete mixture, so the same amount of pigment will more intensely color a mixture with a high cement content than a mass with a low one.
Two or more pigments are used to create shades of cement that differ from the tones of individual colorants. The use of a combined type of coloring requires mixing before adding to the material to obtain the desired shade. This will take more time than coloring with one pigment.
Basic dyes
Iron oxide yellow pigment has weather resistance, light fastness, thermal stability, excellent coloring performance. It is used in the manufacture of concrete products for various purposes, tiles, plasters, roof tiles, many types of primers. Czech and Chinese dyes have similar consumer properties, while the latter are in a lower price segment. Such pigments, created on the basis of ocher, differgranular stable formulation.
Black Iron Oxide Pigment is a persistent chemical substance that has found its application in the manufacture of colored cement products, fillers, and paints. The dry type of dye is distinguished by its covering characteristic and depth of tone, while it does not fade and is not subject to temperature effects, an increased level of alkali. Finished products receive an agate lasting tone.
The red pigment is produced mainly by Czech and Ukrainian manufacturers in the form of a powdered inorganic compound. The base used ensures the durability and saturation of the shade.
White dye is insoluble in organic acids and water, and is non-toxic to humans. Sold in most cases in 25 kg bags.
What determines the degree of staining
The color of the finished products is influenced by the shade of the cement itself. The gray tone has the ability to dim the brightness, so when working with standard Portland cement, it is difficult to get rich colors. The best option is white cement, also used to create blue and green shades.
Each type of material has its own gray color. Different manufacturers also produce cement of the same type, which differs from each other. These differences are seen on colored concrete, with light colored material being more sensitive than concrete having dark iron oxide pigments. So, for one batch of products from this material shoulduse the same cement from the same manufacturer.
The tone of the filler can also affect the final shade of light products. Here, the rule of a single composition is relevant in the production of one batch of goods. There is a significant decrease in this effect in black and blue concrete. The density of the material does not greatly affect the color, but with poor compaction of porous concrete, there is a possibility of efflorescence during storage and use. Their appearance worsens the appearance, they do not affect pigments, but efflorescence is much more noticeable on a painted surface than on a natural one.
Ratio of ingredients
In the preparation of a cement tint mixture, the dosage of the substance by weight should be taken into account, since iron oxide pigments for concrete have different densities. It is also important to observe an equal mixing period, this will allow the mixture to be evenly colored.
Different curing conditions lead to color change. A different shade may appear due to the rapid evaporation of moisture and condensation on the plane, there is also a possibility of a slight coating. To obtain the desired result, it is necessary to observe the proportions of water for diluting concrete and the temperature regime. There is one characteristic pattern: needle-shaped crystals have a high pour point. Small crystals enhance the diffusion of light, making the color appear lighter than similar low temperature cured concrete.
Types of pigments
Iron oxide pigments are usually divided into weak ones, the total critical concentration of which is 25%, and conditionally strong ones, with a concentration of 10%. If it is necessary to obtain a certain shade of more than 10% of the coloring matter by volume of the material, it is desirable to use a smaller proportion of a strong type of pigment. This is because a large proportion degrades the strength characteristics due to increased water absorption.
To create pastel concrete products, it is difficult to set small proportions, so it becomes rational to use a full portion of a conditionally weak coloring matter.
Manufacturers
Among the main manufacturers, German, Czech and Chinese factories are in the lead. In terms of price-quality ratio, Chinese-made pigments are more attractive today. The most widespread among Czechs are red and brown tones. In terms of quality, German dyes occupy the first place, but due to their high cost, their use for paving is unprofitable.
Iron oxide pigments (made in Russia) have a low price and satisfactory properties, due to which they compete with imported ones.
