Iron oxide red has a fading problem in the use of concrete colored bricks

Iron oxide red pigment, as the second inorganic pigment, has been widely recognized by the market in the production of building materials because of its strong coloring power, hiding power and good dispersion. But in use, there will also be some so-called fading confusion, the following common problems are listed as follows:

一、What type of iron oxide red is used to make colored pavement red bricks? Bright color and not easy to fade?

Colored bricks are the most popular cement products on the market at present, and are used in a large number of sidewalks, outdoor building materials, squares, and municipalities. The color of colored bricks is generally: red, green, black, yellow. Iron oxide red pigment is used to make red bricks.

Iron oxide red 130 is mainly nitric acid color is bright red, iron oxide red 190 is mainly sulfuric acid color is jujube red, iron oxide red 110 is mainly sulfuric acid refractoriness high color is light. Among them, it is best to use iron oxide red 190 to make red permeable bricks.

二、Why does red iron dioxide fade after concrete sets?

Cement concrete hydration process to produce alkali, iron oxide red although insoluble in water, but soluble in hydrochloric acid, PH value is very high, it will cause corrosion of iron oxide red color, so it will cause fading.

Cement concrete itself will form a white caustic phenomenon on the surface, and this white will appear to make the illusion of fading red.

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

The long-term effects of ultraviolet light. Iron red is made of iron oxide, an unstable substance that reacts with oxygen in the air to become black iron oxide, which also looks faded.

三、Iron oxide red with water brush on cement products why can drop pigment fade?

Iron oxide red has oxidation reaction, acid-base reaction, aluminum-heat reaction, carbon reduction, decomposition at high temperature and other chemical properties. Only add water because there’s no binder in it, it’s gonna come off. Iron oxide red can be added to cement. Iron oxide red can also be mixed with emulsion in a certain proportion, and then brush on the surface of cement products, so that the pigment can be prevented from fading.

Color fading in the outdoor is normal, there is no absolutely non-fading pigments, iron oxide red in the outdoor long-term exposure to sunlight, the use of temperature changes, air and water containing acid and alkali corrosive substances, will produce color changes in 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 to the appropriate additives to form a protective film on the surface to prevent the influence of climate on the later color.