Year: 1886

page_text: I, HENRY MATHEY, residing at No. 101, Wall Street, in the City of New York,
in the County of New York, and State of New York, in the United States of
America, gentleman, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
My invention relates to a method for coloring cement which will be hereinafter
explained. It is a well known fact that architects, builders & contractors, & others
using hydraulic cements, prefer and demand a dark colored cement.
One reason
is, that, with a dark colored cement an excess of sand is at once apparent: which
does not obtain with cement of a light color.
Many quarries of excellent cement rock have been abandoned for the reason that
when the rock is burned, the resulting cement is of a light color, and on account
of the existing prejudice, it could not be sold at a remunerative price. By my
process such rock could profitably be utilized. By experiments & tests I have found
that the addition of a metallic oxide to the cement gives desirable colors.
principal metallic oxide used is oxide of iron, & I find that not only does this give
color to the cement but adds in some degree to the quality of the cement.
The method of treating the oxide and cement is as follows:
The
The iron ore is first crushed fine enough to pass through about a twenty mesh screen
& is then roasted in a reverberatory furnace, or other suitable apparatus in which
the admission of air can be well controlled, for the transformation of the iron into
an oxide. I conduct the operation of roasting so as to stop at the point where the
greatest part of the iron is transformed by the excess of air into a protoxide. The
material is then discharged & allowed to cool gradually, & protected from contact
with the air during the cooling process: thus preventing absorption of one more
atom of oxygen, & transforming the protoxide into a peroxide. The coloring
power of both oxides is great: but the dark oxide (protoxide) gives the most
desirable color. The iron is then added in a suitable proportion (from 2%
10% more or less) to the cement before the final pulverization, & they are
pulverized together. This trituration diffuses the iron uniformly through the
cement & causes it to assume a homogeneous tint.
to
Not only is a desired tint obtained, but I find that the paste of cement sets
smoother and quicker and the tensile strength increased. It may be that some
clays are rich enough in iron to give the desired color when burned & added to the

page_text: cement. This may be done without departing from the spirit of my invention.
I may of course use other metallic oxides than iron and obtain other colors. It
may he that the oxides used shall be in a greater or less per cent than here
stated this depends on the work to be done, as, for example, plastering, side-
walks, &c., &c.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is,
1. The process of coloring cement which consists in adding to the ground cement
rock before final pulverization, a metallic oxide which is diffused through the
cement during the final grinding or pulverization.
2. The process of coloring cement which consists in adding to the cement rock
before final pulverization, burned clay.
3. The process of coloring cement and adding tensile and breaking strength
thereto which consists in adding to the ground cement rock before final pulveriza-
tion a metallic oxide burnt separately from the cement rock and then the burned
rock and oxide ground together.