Application of Dyes and Pigments |
Cement Industry
Since many years, people have developed many
interesting effects by mixing cement and pigments in different ways and
in different proportions. Concrete is derived from cement. For about
last one century, pigments have been using with concrete to give them
different colors. When pigments are mixed with concrete, then actually,
these pigments tint the color of the paste portion of the concrete.
To ensure a long lasting cement color shade, the
pigment that is being used in the cement, must have a good quality.
These pigments (color) are made from both natural and synthetic Iron
oxide, cobalt, titanium dioxide and chromium oxide. From iron oxide
pigments, red, black and yellow color can be obtained. From cobalt
pigments, blue color can be obtained. White color and green color can be
obtained from titanium dioxide and chromium oxide respectively. Other
colors like buffs, brown, tans, coppers, oranges, chocolates and many
other colors can be obtained from the blends of the red, black and
yellow colored iron oxide pigments. These colored pigments are: water-
wetable, lightfast, alkali resistant and will not negatively effect the
firmness and strength of the cement. But, one thing should we remember
about the concentration of these pigments in the cement. This
concentration should be within the range of 10% of the weight of the
cementitious ingredients. Iron Oxide Pigments One of the most commonly used pigments with concrete is Iron Oxide Pigments. Iron Oxide pigments are combined with concrete to protect the concrete form fading or prevent the leaching out of concrete. The primary colors of Iron Oxide Pigments are available in red, yellow and black. With the red colored Iron Oxide pigments, shades of blue or orange can be found. To create multitude of colors, these pigments having of different colors are combined together according to a certain ratio. Still today, the use of Iron Oxide pigments is maximum. The few reasons of this popularity of this pigments in the cement industry are:
Chromium Oxide Chromium Oxide generates the green effect in the cement. But, it is expensive one. So, it is used in some special cases. Cobalt Cobalt generates the blue effect in the cement. But, it is expensive one. So, it is used in some special cases. Titanium Dioxide Titanium dioxide produces the white color effect in the cement and other related materials.
In general, pigments don't react with cement, because
pigments are inert in nature. So, pigments are not be counted as
cementitious material contents. Then, the question arises, that how
pigments are applied with cement. Actually, whenever pigments are mixed
with cement then, these pigments form color of cement grains. This is
possible, because pigments bond with the cement via the hydration
process.
The different pigment that are used in cement
industry, are available in different forms. These different forms are:
Powdered form, Granular form and Liquid form. Although, pigments work
well in all three different forms, but, these require different handling
process and composition should be different. However, the oldest form of
pigments is the powder form.
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