A summary of the discoloration of ferric oxide red in the use of concrete colored bricks

December 07, 2022

Iron Oxide Powder 145 Jpg

As the second ranking inorganic pigment, ferric oxide red pigment has been widely recognized in the market for its strong coloring power and good dispersibility. However, there are also some so-called confusion of fading in use. The following are the common problems:

I. What type of Iron Oxide red is used to make colored pavement red bricks, which is bright and not easy to fade?

Colored bricks are the most popular cement products in the market at present, which are widely used in sidewalks, outdoor building materials, squares, municipal administration, etc. The color of colored bricks is generally red, green, black and yellow. Iron oxide red pigment is used to make red bricks.

Iron oxide red 130 is mainly the bright red color of nitric ACID, iron oxide red 190 is mainly the purplish red color of sulfuric acid, and iron oxide red 110 is mainly the light color of sulfuric acid with high fire resistance. The best way to make red permeable bricks is to use ferric oxide red 190.

Why does ferric oxide red fade after concrete setting?

1. Alkali is produced during the hydration of cement concrete. Although iron oxide red is insoluble in water, it will be soluble in hydrochloric acid. With a high PH value, it will corrode the color of iron oxide red, so it will cause discoloration

2. The cement concrete itself will form white efflorescence on the surface, which will make the false appearance of red fading.

3. Cement concrete will breed mold, black spots, absorb dust, etc. in a humid environment for a long time, which will also cause the color to be covered, forming the false appearance of fading.

4. Long term effect of ultraviolet ray. The component of ferric oxide red is ferric oxide, which is an unstable substance. It reacts with oxygen in the air and becomes black ferric oxide, which also looks faded.

Why does ferric oxide red paint fade when it is brushed on cement products with water?

Iron oxide red has the chemical properties of oxidation reaction, acid-base reaction, aluminothermic reaction, carbon reduction, decomposition at high temperature, etc. Only add water, because there is no adhesive in it, it will definitely fall off. Iron oxide red can be added to cement. You can also mix ferric oxide red with lotion in a certain proportion, and then brush it on the surface of cement products, so as to prevent the fading of pigments.

It is normal for the color to fade in the open air. There is no pigment that will not fade. Iron oxide red is exposed to sunlight for a long time in the open air. Changes in temperature during use, as well as acid and alkali corrosive substances contained in air and water, will change the color of iron oxide red products.

In order to prolong the color change of iron oxide red products, high-quality iron oxide red paste can be mixed with concrete cement in proportion, and then appropriate additives can be added to form a protective film on its surface to prevent the influence of climate on the color in the later period.

Author:

Ms. Yolanda

E-mail:

info@jinhetec.com

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+86 13298161700