Improvements in the Process of Manufacturing Artificial Stone.
Year: 1898

page_text: Date of Application, 30th Nov., 1898
Complete Specification Left. 23rd Aug.. 1899-Accepted 25th Nov.
1893
PROVISIONAL SPECIFICATION.
Improvements in the Process of Manufacturing Artificial Stone.
I, REGINALD HADDAN, of the Firm of Herbert Haddan & Co., of 18, Buckingham
Street, Strand, W.C., London, Patent Agent, do hereby declare the nature of this
invention, a communication to me from abroad by Rudolph Koepp & Co., of
Oestrich a/Rhine, in the Empire of Germany, to be as follows:-
Hitherto artificial cement stone has been manufactured in the following
nanner:-
Cement mixed with water is put in a casting mould and remains there till it
is entirely set. Then the block so cast is taken out and dried. The method of
working is always the same even when for augmenting or diminishing the
weight, fibrous material, fabrics, cane, or the like is mixed therewith.
.
In all cases the setting of the cement is founded on the fact that a part of the
water added to the cement is combined with it in crystallization. This process
results in enlargement of volume and generation of heat, the latter is transferred
to the remaining water and gives also an augmentation of volume. This double
effort of expansion together with the progress of the reaction effects naturally
a movement of the mass whilst setting and so part of the cement particles is
suddenly torn asunder just as it is setting whereby it naturally looses part of
its theoretically possible hardness.
We prevent this disadvantage by a simple improvement.
After the paste is cast into the mould, we take away a large part of the water
employed by suction. It remains then a wet mass containing more than sufficient
water for the reaction possessing plenty of capillaries filled with air. In this
porous mass the single cement particles have room to expand and to join one
another tightly without expanding the volume of the whole mass.
This artificial stone grows as hard as natural stone.
The suction effect is obtained by air-pumps, water or steam jet blast, porous
layers, or the like.

page_text: In all cases the setting of the cement is founded on the fact that a part of the
water added to the cement is combined with it in crystallization. This process
results in enlargement of volume and generation of heat, the latter is transferred
to the remaining water and gives also an augmentation of volume.
This double effort of expansion together with the process of the reaction effects
naturally a movement of the mass whilst setting and so some of the cement
particles are suddenly torn asunder just as the mass is setting whereby it naturally
loses part of its theoretically possible hardness.
This disadvantage is prevented by a simple improvement.
After the mass is
cast in the mould, a large part of the water employed is removed by suction.
There now remains a wet mass containing more than sufficient water for the
reaction possessing plenty of capillaries filled with air. In this porous mass the
single cement particles have room to expand and to join one another closely
without expanding the volume of the whole mass.
This artificial stone becomes as hard as natural stone.
The purpose of the suction is the removal of the water deposit between the
single particles of the gypsum or cement mixture. If the material to be partially
dried consists entirely of equal small particles, a quick suction is effected but if
the mass is unequal as for instance a mixture of cement with sand and stones,
it is preferable to conduct the suction slowly in order to prevent the fine parts
being separated by being washed by the quick flow of water from the surface
to the bottom of the blocks which would thus become unequally hard. The
suction used may vary in a large degree according to the thickness of the blocks;
the thicker the same are, the greater it must be. The best and quickest working
will be with a vacuum of 40-50 cm.
Also with very little suction it is possible but in a much slower manner to
naturally exercise the same effect by the use of porous bases which operate only
by capillary attraction. The bases can be of all materials containing capillaries,
for instance gypsum plates, tufaceous stone, sponge or carbon and the like and
are used covered with a fine meshed web as a mould base or placed on the top of
the blocks.
If the bases are full of water they must be dried before being used again.
The suction effect is obtained by means of air-pumps, water or steam jet blasts,
or by the before described porous bases to the moulds, or the like.
The manner in which the moulded blocks are subjected to suction is according
to the form of the blocks desired. If they are solid objects with smooth surfaces
for instance wall plates, it is more simple to use a suction table with perforated
surface on which the mould, which itself is not adapted for suction is placed. If
more complicated objects are formed, for instance, hollow bodies, the mould itself
or the core, are made the suction base as the parts of the core coming in contact
with the moulded object are wholly or partly perforated and brought into con-
nection with a vacuum chamber.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
-
An improved process for manufacturing artificial stone containing as essential
ingredient cement in which, after the mass has been poured into the mould, a
part of the water originally used is removed by suction before the cement has
set hard.