IMPROVEMENTS IN THE MANUFACTURE AND EMPLOY- MENT OF CEMENTS AND LIMES
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by Jean Ducournau at the Office
of the Commissioners of Patents, with his Petition, on the 22nd
December 1875.
I, JEAN DUCOURNAU, of Paris, France, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE AND EMPLOY-
MENT OF CEMENTS AND LIMES," to be as follows
This Invention relates to a new composition or mixture for improving.
cements of all kinds and limes, thereby rendering them stronger and
harder, while at the same time they are not so liable to crack as
heretofore.
"
Fi
I have found that the presence of quicklime which is found in
cements and particularly in newly made cements is a great drawback to
their immediate use, but by means of my new composition these incon-
veniences are remedied, and the following advantages obtained:-
"
.1.
1. It dissolves the quicklime which is always found in great quantity
in newly made cements.

page_text: 3. It increases their durability as well as their strength in proportion
to their age.
4. It gives to bydraulic lime a perfect setting producing at the end of
a few months an artificial stone as fine and as compact as natural stone
used in buildings.
5. It improves the concrete used in foot paths or other similar works.
6. It prevents the cracking and pulverizing of those exposed to the
influence of the atmosphere or sun. In fact it may be applied with
security for all sorts of works exposed to the influence of the atmosphere
and continual traffic, which hitherto has presented so much difficulty and
uncertainty that rendered the application of such materials very
expensive, and in most cases impracticable.
I have also found a simple means for chemically analyzing and
experimenting, whereby I am able to ascertain with precision the quality
of the cements, it indicates in fact the quality of the manufacture, their
age, or how long they have been made, their nature or otherwise, if they
are slow setting cements, as Portland cement, or quick setting cements
or Roman cements, what quantity of free lime they contain, and if
the lime is in quick or slacked state, and what resisting power they
possess.
The base of the compound is azotic or any other suitable acid, it may
be used in either a liquid or solid state, and the object of the acid is to
dissolve the quicklime contained in pulverized cements and lime, and
to relax the setting of newly made cements in order to impart to the
silicates a complete and regular transformation. This compound when
in 'a liquid state is composed of azotic acid diluted in one, two, three,
four, or five parts of water, according to the material to be rectified,
and the length of time since the cement has been manufactured; this
compound is particularly adapted for artificial stone making.
The solid mixture is composed,-

page_text: it with the cements or lime at the time they are to be applied, and
which are desired to be rectified; this mixture may also be added to the
cements sometimes befôre they are to be made use of.
which are desired to be rectified; this mixture may also be added to the
cements sometimes before they are to be made use of.
Artificial stone is best obtained by means of the liquid compound
herein before described, and the most convenient proportions for this are
as follows:-
dededement
100 parts of hydraulic lime.
100 parts of soft stone pulverized and sifted through a No. 50 sieve:
100 parts of water to which 5% of azotic acid is added.
After being well stirred this compound is placed in moulds, and taken
out when set which may be done in three or four days?",
Marble, silex, glass, and also sand may be used instead of the
pulverized stone, but all of these ingredients: must be sifted through a
No. 50 sieve. This kind of stone is soft and can be worked and cut as
natural stone; if it be desired to obtain a harder stone, pulverized
Portland or other cement must be substituted for the powdered lime.
The solid compound is made of 20 parts of silex powder or of any
other hard stone sifted in No. 80 sieve, afterwards mixed with 8 parts
of azotic acid to form a soft paste, afterwards to this soft paste is
added and mixed 100 parts of particles or grains of silex or other hard
stone sifted in a No. 50' sieve, afterwards dried and kept in casks.
If the powder to be rectified is of recent manufacture at the time of
mixing the material 10% of the last named composition must be added
to it; if the cement to be operated upon is not to be applied before the
expiration of a month 6% of the composition will suffice, and if it is not
to be used for three or more months 3% will suffice.
Plastic concrete was manufactured in 'the year 1855 by the same
Inventor, its excessive hardness has caused its very general use for foot-
paths where great traffic takes place, but there is a defect in it inherent
to all cements, that the quicklime contained in them caused frequently
that concrete to crack, and by this defect prevented its use as covering
for terraces and great numbers of other hydraulic constructions, but
now by the addition of the mixture herein-before described the concrete
made according to this Invention becomes a product which owing
to its various applications constitutes a very important auxiliary in the
building art.

page_text: According to my present Invention the plastic concrete is composed
of Portland cement, and of hard materials in small pieces, such as silex,
quartz, granite; for the ordinary plastic concrete, the materials must be
broken up into small pieces, but for the marble plastic concrete they
need not be quite so small as for the plastic concrete.