AN IMPROVED TREATMENT FOR THE PRODUCTION OF RAW MATERIAL FOR ASPHALT PAVING OR SIMILAR PURPOSES
Year: 1884

page_text: DEBOLTIVATION
I EMIL DIETRICH, of Berlin in the Empire of Germany, Professor at the Royal
Polytechnical High School Berlin, do hereby declare the nature of my Invention
for AN IMPROVED TREATMENT FOR THE PRODUCTION OF RAW MATERIAL FOR
ASPHALT PAVING OR SIMILAR PURPOSES, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
Besides the usual preparation of the asphalt stone of certain quarries (Val
Travers, Seyssel, Lobsann, Ragusa) which consist exclusively in reducing the
bituminous stone to small pieces by mechanical means, such material for paving or
other similar purposes has also been obtained in a commercial manner, by mixing
the powder obtained from such quarries in cases where it contained too much
bituinen, being workable, but causing certain defects when forming a surface (the
softening of the pavement or formation of waves thereon, etc.) with powder con-
taining less resinous substances of the same or other quarries or by heating the
same without any addition (in a rotating vessel) for a considerable time and for
the purpose of extracting the superfluous contents of bitumen in a suitable
manner.
The only object in view now is therefore to improve the powder which to a
certain extent is already suitable for stamping or rolling purposes.
The inventor of these improvements has, in his work entitled " The Asphalt
Streets."
(Berlin 1883) page 48 already named two ways in which it night be
possible to impregnate artificially natural limestone or asphalt stone containing not
enough resinous substances with bitumen, and thereby make the same suitable for
being afterwards stamped or rolled, by mixing the reduced stones with bitumen
which is dissolved by easy volatile dissolving means and afterwards absorbed by
warming the mixture or by letting bituminous vapours act on limestone powder,
which will also cause it to be absorbed by the latter in a similar manner,
r, as very
likely is the case in the formation of the asphalt stone in nature.
The first named treatment or a similar one is already patented in Great Britain
(Farrington) but in practice no satisfactory result has been obtained thereby, as the
added dissolving means cannot be absorbed from the mixture in a suitable short
time. The second treatment has for its difficulty that the bitumen parts by very
different temperatures do not penetrate the stone-powder uniformly.

page_text: Better results are expected to be obtained from another treatment tried but
hitherto not yet described which has for its object to convert pure or bituminous
limestone, which by itself is not suitable for undergoing the stamping or rolling
operation, or which possesses the named defects into a suitable material, by changing
the disposition of the bitumen which is likely to be already contained in the stone
without the addition of the material exclusively employed heretofore, for stamping
or rolling purposes from Val Travers, Lobsann, Seyssel, Ragusa,
The treatment consists in incorporating to the lime or asphalt stone during the
time suh, stone is reduced into small pieces, pure bitumen in a consistent state,
paste form, also Trinidal, Epuré, Goudron or other bitumen, getting liquid and
volatile under a particularly high temperature and afterwards conducting the
mixture into rotating vessels or similar appliance, for the purpose of warming and
uniting the same, whereby the softened bitumen is absorbed by the line-tone
particles. The sort of bitumen to be added, is depending on the sort of bitumen
contained in the asphalt stone, and on maintaining thereby the consistent paste-
like aggregate state liable of splintering in the disintegrator, in order that the
mixing can be performed in a cool room, or in case of need in a room cooled
artificially.
Experiments have proved that by this treatment a powder well suited for under-
going the stamping or rolling operation can be produced.
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 :-
Mixing mechanically, pure or bituminous limestone in the form of powder, with
pure bitumen, also in the form of a powder and then causing the finely-powered
bitumen contained in the stone powder, to be absorbed by means of heating the
same in a rotating vessel, or other similar appliance for the purpose of producing &
raw material suitable for asphalt paving or similar purposes.
EMIL DIETRICH,
Pr. Bosshardt & Grant.