A Process for Manufacturing from Roman Cement a Composition similar to Portland Cement.
Year: 1890

page_text: Date of Application, 12th Sept., 1890
Complete Specification Left, 5th June, 1891--Accepted, 12th Sept., 1891
TRUVIDIUNAL DILETATION.
A Process for Manufacturing from Roman Cement a Composition
similar to Portland Cement.
I, CARL VON FORELL, Director of Cement Works, Braunschweig, in the German
Empire, do hereby declare the nature of this invention to be as follows:-
This invention relates to a process for manufacturing from natural hydraulic
limes constituting what is called Roman cement, a composition similar to Portland
cement and possessing its binding, quick setting and other properties. The
process is as follows.
Roman cement or clay-marl such as is used with a mixture of lime in the manu-
facture of Portland cement, is burnt until the carbonic acid is driven off and is then
reduced to a fine powder. The powdered material is then mixed with powdered
hydrate of lime in the proportions usual in the manufacture of Portland cement, the
composition being then ready for use.
Instead of the hydrate of lime, granulated dried and finely powdered blast
furnace slag can be used, or a mixture of slag with hydrate of lime. The cement
produced is nearly the same in all cases.
This process presents the following advantages.
Besides economy in production resulting from diminution of the power required,
there is important saving from the fact that the thorough burning of the whole
mass required for producing Portland cement from lime is unnecessary, because it
suffices to heat the clay marl to a temperature under that required for cement
burning, and besides a less quantity has to be treated in the furnace. Moreover in
this process for a portion of the Roman cement may be substituted slag or other
material rich in lime or clay.
Dated this 12th day of Sontember 1800
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
A Process for Manufacturing from Roman Cement a Composition
similar to Portland Cement.
I, CARL VON FORELL, Director of Cement Works, Braunschweig in the German
Empire, 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:-
-
This invention relates to an improvement in the manufacture of artificial Roman
cement and consists in adding to ordinary Roman cement or natural hydraulic lime
such a quantity of finely powdered hydrate of calcium that the mixture obtained
contains lime and hydraulic factors in the proportion of about 17 to 1.
A product of this kind possesses the binding, quick setting and other properties
of ordinary Portland cement.
The manner in which this product is obtained, is as follows:
Roman cement or clay marl of any composition such as is used with a mixture of
lime in the manufacture of Portland cement, is burnt until the carbonic acid is
driven off and then reduced to a fine powder. The powdered material is then
mixed with powdered hydrate of calcium in such quantities that the total amount of
lime on the one hand and the hydraulic factors (silica alumina and iron peroxide)
on the other hand are in the proportion of about 1·7 to 1. The mixture obtained is
then ready for use.

page_text: Instead of the hydrate of calcium, granulated dried and finely powdered blast
furnace slag can be used or a mixture of slag with hydrate of calcium. The cement
produced is nearly the same in all cases.
The proportions of the above named ingredients required for obtaining the said
proportion of 1 to 1.7 between the hydraulic factors and the lime, will be variable
according to the chemical composition of the materials employed. By way of
example it may be stated that if the composition of the Roman cement be taken
as 58 p.c. of CaO and 42 p.c. of R2O3, while that of the hydrate of lime be
taken at 75 p.c. of CaO and 25 p.c. of H,O, then the proportions would be
100 parts of Roman cement, and 17 parts of hydrate of lime.
Or, when using half blast furnace slag of the composition of 52 p.c. of CaO
and 48 p.c. of R,O, and half Roman cement of the composition of 70 p.c. CaO
and 30 p.c. R₂O, with the same hydrate of lime as above, then the proportions
would be 50 parts of blast furnace slag, 50 parts of Roman cement and 7 parts of
hydrate of lime, for obtaining the above proportion of 1 to 1.7 for the hydraulic
factors and the lime. I wish it however to be distinctly understood that I in no
way limit myself to the above proportions, as they are only given as examples.
This process presents certain important advantages, for instance besides economy
in production resulting from diminution of the power required, there is an important
saving resulting from the fact that the thorough burning of the whole mass required
for producing Portland cement from lime is unnecessary, because it suffices to heat
the clay marl to a temperature under that required for burning Portland cement
and therefore only a comparatively small quantity of fuel is required.
Moreover in this process for a portion of the Roman cement may be substituted
slag or other material rich in lime or clay.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The process for manufacture of a composition similar to Portland cement by
mixing burnt and finely powdered Roman cement with calcic hydrate.
2. The process for manufacturing a composition similar to Portland cement by
mixing burnt and finely powdered Roman cement with granulated dried and
powdered blast furnace slag.
3. The process for manufacturing a composition similar to Portland cement by
mixing burnt and finely powdered Roman cement with hydrate of lime and blast
furnace slag.
Dated this 1st day of June 1891.
ABEL & IMRAY,
Agents for the Applicant.