Improvements in and relating to the Production of Asphaltic Composition in the Form of a Powder or of a Mastic.
Year: 1894

page_text: COMPLETE SPECIFICATION.
Improvements in and relating to the Production of Asphaltic
Composition in the Form of a Powder or of a Mastic.
I, CHARLES HENRY SLICER, a citizen of the United States of America, residing
at 22 West Biddle Street, in the City of Baltimore and State of Maryland, one of
the United States of America, Solicitor of Patents, 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 an improved asphaltic composition powder for surfacing
roadways, paving streets, and like purposes; and my said invention consists in the
process, and in the product thereof, whereby an asphaltic carbonate of lime rock
composition is produced, whose constituents, qualities and conditions shall, when
desired, be substantially identical with those of the natural asphaltic carbonate of
lime rock powder, commonly known as "Neufchatel carbonate of lime rock
powder," and at a cost so greatly less than that of this natural rock powder, as to
admit of its general use for paving and surfacing purposes.
For many years it has been well known that for surfacing streets, roadways and
the like, there has not been in use, or put before the public, anything in durability
and other desirable qualities of near resemblance to the Neufchatel rock powder.
This natural product is peculiarly constituted in having the condition, quantity and
quality of its carbonate and asphalt so fixed or determined and evenly commingled
or diffused as to admit of the rock being disintegrated and reduced to powder by
the application of heat, or by mechanical means, such as disintegrating rollers, for
separating the particles to a fine, clean, dry powder, either in a hot or cold
condition. This operation is such as to separate the grains, which are only bound
together in the rock by the asphalt, into powder, without crashing the grains, and
leaving the natural coating of asphalt upon the grains intact. This powder when
in a hot state can be sifted through a sieve having a mesh of thirty or forty to the
inch, or otherwise spread upon the roadway, etc., when properly prepared to receive
it, and being then tamped, becomes a solid more durable than granite for street and
road wear.
Hence the Neufchatel powder has set the standard of excellence by
which all other asphaltic materials, for like purposes are or may be measured
or determined.
In order to give a full description of my improved asphaltic carbonate of lime
rock powder, and process of producing it, it is necessary to state here the kind.
conditions, and proportions of the materials composing the natural Neufchatel rock
powder as disclosed by analysis by different authorities from the year 1837 to the
present time. These authorities differ as to the exact quantity of asphait and
carbonate of lime contained in the natural powder or rock, but all agree in fixing
the quantity of asphalt anywhere from eight to twelve per centum of its weight, and
the carbonate of lime is given as eighty-five to ninety-two per cent., and moisture,
silica, etc. as five per centum. Fully fifty per centum of the lime powder is of
exceeding fineness, readily passing through a sieve having a hundred mesh to the
inch, while the balance will pass through a mesh of respectively sixty, forty, and
thirty to the inch. The condition of the asphalt when separated from the
carbonate is semi-fluid or plastic. The great durability and wearing qualities of
the Neufchatel powder when in use, is almost if not wholly due to the extremely
fine comminution of over fifty per centum of its lime carbonate. This means nearly
five times the weight of the asphalt is flour carbonate, the fine being generally
in excess of the coarser particles of the carbonate. This should always be the case
in making asphalt carbonate material where good quality of roadway material is

page_text: required. It is by following the conditions and facts shown in the natural
Neufchatel rock that I am enabled to produce an asphaltic carbonate of lime rock
powder substantially the same as the Neufchatel, by the process which I have
discovered and which I will now state.
I take pure asphalt, or that of eighty-eight to ninety-five per centum purity.
I prefer it in a natural plastic state, such as can be readily drawn by handling at a
temperature of sixty degrees Fahrenheit into threads or ribbons. But if the
asphalt be not naturally in a plastic or semi-plastic condition for use, I bring it to
this plastic condition by the addition and incorporation by heat, of heavy gravity
petroleum oil, as now commonly practised by the trade to produce asphaltic cement
commonly used in the trade; and the foregoing refers to the state of the art as now
practised in its best and most durable form.
I take one part by weight of this plastic asphalt and add to it about fifty per centum
of its weight of benzine, gasoline, or like solvent, or sufficient solvent to bring it to
the proper fluid condition. By this means the asphalt can be readily reduced to a
cream like fluid. When this is accomplished add and stir into the asphalt fluid
about nine parts by weight of carbonate of lime rock powder in a condition of
comminution as follows: Take about fifty per centum of the nine parts, by weight,
that is to say, about four and a half parts to five, which shall pass readily through
a sieve having a mesh of one hundred to the inch, while the balance of the nine
parts shall pass respectively in about equal portions through a sixty, forty, and
thirty sieve. This large quantity of carbonate of lime flour and powder will very
readily and quickly mix with the asphalt, each and every particle of the carbonate
of lime becoming thoroughly and uniformly coated. It should be noted that as
little of the benzine or solvent should be used as may be found practicable in
bringing about the perfect and uniform coating of the particles of carbonate, just
enough to leave the powder as little moist as possible after the mixing. This is for
the reason that the solvent serves no other purpose than to allow the ready and
uniform and proper degree of coating of this large quantity of carbonate of lime
powder with the asphalt, as the solvent must be removed from the asphaltic lime
powder before the powder is ready for use, and therefore, the less to remove
the better.
The next and most important step in my process, is the heating of the asphaltic
lime rock mixture, in order to fuse and cement by heat the asphaltic coating
that is upon the particles of lime rock powder. This fusion of the asphalt by
heat is necessary after the use of the solvent, since the evaporation of and the
passing off of the solvent from the asphalt coating upon the particles of carbonate
of lime, leaves the coating porous, or as it were, in the condition of impalpable
powder. Hence the application of heat to fuse the asphalt back to its full
cementing, adhesive tenacity and toughness around the particles of powder.
The solvent can be driven off in various ways, or it may be allowed to pass off
by evaporation. A rapid way to get rid of it is to vaporize the benzine by an air
blast. But the most practicable and economical method is to drive out and off the
moisture of the solvent by heat. This method gives the advantage of continuing
the heat after the evaporation of the solvent to bring about the fusion of the
asphalt coating around the particles of carbonate. The heat for this operation
may be from two hundred to two hundred and fifty degrees Fahrenheit, which
leaves no danger of impairing the quality of the asphalt or lime carbonate in the
mixture. In treating asphalt for the mixture for road purposes solely by heat as
usually practised, great heat is required and results many times in impairing and
often burning and even ruining the quality of the material. Another reason for
applying heat for both driving off the solvent and for fusing the asphalt at the
same time, is, that it gives the advantage of collecting and condensing the
vaporized solvent by means of a still worm, or other suitable condensing device,
thus recovering the solvent for use over again. This recovery of the solvent for
use over again adds greatly to the economy of producing the asphaltic carbonate
of lime powder.

page_text: It must be understood that the heating of the powder for fusing the asphalt
that is around the particles of carbonate, may be done at any time, that is to
say, after the mixing of the fluid asphalt and carbonate is accomplished, as I
have before stated, or after the solvent has passed off by natural evaporation,
or has been driven off by air blast; or the heating of the material may be put
off and effected at the time of using. This beating, however, for laying the
material, is sufficient to bring about the necessary fusion of the asphaltic coating
around the particles, as heretofore stated. If the heating for laying the
material is done without a previous heating for the specific purpose of effecting
the evaporation and fusion alone, then such heating is within the spirit of my
invention.
The material when used either with solvent present or with solvent passed out
without heating the material for fusing for laying, is but poor stuff for roadway,
street, and like purposes.
The following is a simple method of mixing and producing my asphaltic
carbonate rock powder.
Take the proper proportion of powdered carbonate of lime rock, and place it
in a suitable metal vessel. Then take the proper quantity of asphalt made fluid by
solvent, and pour into the vessel having the carbonate of lime powder. Then stir
the mixture with a paddle or other like device by which the mixing or coating of
the particles of carbonate with asphalt is easily and readily accomplished. Heat
is then applied under the vessel to bring about the fusion of the asphalt upon the
particles, which at the same time drives off the solvent. This driving off the
solvent and fusing the asphalt is accomplished very rapidly, particularly if
the powder is stirred well during the heating. When this operation is complete,
is readily determined by examining the powder, which will be found free of any
solvent moisture, and granular.
This product is carbonate of lime asphalt powder, and while yet hot is now
ready for use, and by sifting it through a sieve or otherwise spreading the powder
on the surface of the roadway or street to the proper thickness and tamping it
with hot tamps, or rolling, it is brought to a solid surface and when cold becomes
hard and will stand attrition from hard traffic longer than stone. In a word, the
operation of using the material is the same as that well known and practised in
the use of Neufchatel powder.
Instead of using the powder at once as herein stated, it may be allowed to cool,
and when cool, stored in bulk, or in bags for future use, transportation, and sale.
It improves in quality by age, and to use this stored material, it is only necessary
to heat the powder to two hundred or two hundred and fifty degrees Fahrenheit in
any suitable revolving cylinder.
Another quality of this asphaltic carbonate of lime rock powder as produced by
my process, is that after it has been used on streets for years, or elsewhere, it,
like the Neufchatel powder, can be taken up again, reduced to powder by heat, and
again relaid without the addition of new material of any kind, with equal if not
better results than when first laid.
I do not confine myself to the use of pure asphalt, or that of eighty-five or
ninety per centum pure, as herein mentioned, as I may use Trinidad, Cuban, or other
like asphalt; but as these last mentioned asphalts, when sold, even as being refined,
contain a very large percentage of almost impalpable inert matter, not soluble or
reducible to fluid, either by heat or benzine, or the like, they would of course,
coat greatly less proportion of flour or powdered carbonate of lime rock to a
given quantity of these asphalts, in producing asphaltic carbonate lime powder;
and of course, these friable asphalts must be brought to a plastic state by the use
of oil, as herein stated, before they are used for coating the carbonate powder by
my method. In fact, any of the natural asphalts, whether fluid or semi-fluid, as
well as the solid and hard, can be used for making the asphaltic carbonate powder
by following my process carefully.
Nor do I confine myself by my process to making only an asphaltic carbonate

page_text: powder of the very high grade quality of the Neufchatel powder, as it is obvious
that for many purposes my powder is of a finer and better quality and of greater
cost than necessary.
Hence by using the carbonate of lime powder to be coated
of a grade less particularly fine, the same quality of asphalt will coat perfectly
and readily a greater quantity of carbonate, ten or even twelve parts to one, instead
of nine parts to one, as before mentioned, and still give an asphaltic carbonate of
lime powder not equalled by any roadway or street material on the market, except
the Neufchatel, and at a lower cost than that containing nine parts of finer
carbonate, before mentioned.
It will be understood that carbonate of lime powder and sand, or sand alone, or
other finely comminuted stone or like material can be used for being coated with
asphalt for making a roadway or paving material by my process, and these come
within the scope of my invention, but the lime powder for coating with asphalt,
will in the end prove of the greater economy.
A very desirable condition in which to use the carbonate of lime for being
coated, as herein set forth, instead of having it of various degrees of coarseness
above sixty mesh sieve, is to have the carbonate powder all pass readily a sixty
mesh sieve. This gives a fine powder running up in fineness to and passing a
hundred mesh, and while this gives a splendid asphaltic carbonate powder, it is,
more readily and economically worked than following the conditions of the natural
powder as regards the variation of sizes of the particles of carbonate.
In the mixing and coating of the granules of carbonate of lime-rock with the
fluid asphalt, which is done before heating, the carbonate should be continued to be
added until the mixture when put under heat should be freely and clearly granular
and remaining almost freely granular when cold.
It will be understood that in this granular condition there should be enough and
perfect coating to bring about perfect adhesion of the particles of powder when
hot and being tamped.
This asphaltic carbonate of lime material as a product for use in surfacing
roadways, streets, and the like, is distinguishable from mastic and other products
on the market by reason of being in clean powder form and ready for heating,
sifting and spreading.
It will be understood that for heating the powder for the purposes stated, the
heat may be applied to the mixing vessel; and for the recovery of the vapors of
the solvent, an ordinary still worm may be used with the mixing vessel, and as such
appliances are well known, their illustration is deemed unnecessary.
One of the most important advantages of this process is, that any of the natural
asphaltic rocks too poor in the quantity of asphalt they contain to be used in
powder form in making roadways, can be brought to the proper standard of quality,
so that they may be as readily used in powder form as is the famed Neufchatel
rock powder. To do this, all that is necessary is to reduce these rocks to powder,
and then add to the powder the required amount of asphalt in fluid form, after the
same manner of treating the lime-rock powder as hereinbefore set forth. But
the amount of fluid asphalt to be added must of course be with due regard to the
amount of asphalt already naturally present in the asphaltic rock powder.
I do not confine myself in this process to the production of asphaltic composition
powder, but also produce asphaltic mastics.
To make the composition in the form of a mastic I take Neufchatel, Parymont,
St. Ambroix, or other asphaltic lime-rock powder, or I take the rock and reduce
it to powder. After ascertaining how much asphalt this rock or powder contains
and how much more will be required to be added to bring the powder to a mastic
condition, I then take by weight the proper amount of asphalt that is plastic at a
temperature of from 60° to 80° Fahrenheit. To this asphalt I add fifty or more
per centum, as may be required, of benzine or like solvent, enough to reduce the
asphalt to a thick fluid condition. I then take the required weight of the rock-
powder to be treated and put it into a vessel and add to it the quantity of asphalt
desired, already made fluid by the solvent, and stir the mass to thoroughly mix it.

page_text: In this mixing the solvent keeps the mass in a fluid condition until the incorporation
of the asphalt with the powder is complete. The solvent is then driven off or
removed from the mass by the application of a moderate heat, say from 200°
to 212° Fahrenheit. This heat will not only vaporize and drive off the solvent,...
but will fuse and densify the asphalt mass and leave a mastic of prime quality
ready for use by spreading at once. Or it may be made into blocks or cakes for
subsequent use as a mastic by re-heating.
The quantity of asphalt necessary to be added to the asphaltic rock powder
depends upon the quantity of asphalt already present in the powder; and also upon
the purity of the asphalt to be added. A good quality of Neufchatel rock-
powder would require to have added to it asphalt of ninety per centum purity to
the amount of from six to ten per centum of the whole weight of the powder, in
order to make the powder into a mastic, and it will be understood that the mastic
can be made rich or poor, as may be desired.
Seyssal, Brunswick, or Vorwohler asphaltic lime rock powder which are low
or poor in the quantity of asphalt they contain, and the lime-rock powder being.
coarser than that of the Neufchatel, they would require a different amount of
asphalt to be added, and this can readily be ascertained, as in the case of the
Neufchatel.
All other things being equal, the coarser the lime powder in the rock, the less
asphalt is required to be added to make these rock powders into mastic. In making
mastic from simple rock or lime-rock powder, the process is the same as in the case
of the asphaltic lime-rock powder, only there being no asphalt present in the
simple rock powder, the quantity of asphalt to be added to produce mastic is
greater. The lime rock or other simple rock is reduced to powder by grinding or
otherwise, and the plastic asphalt reduced by the solvent is added to and thoroughly
mixed with this powder, and the solvent is then removed. The quantity of asphalt
required to be incorporated with the simple rock powder depends upon the degree
of comminution of the powder. If fifty per centum of the powder passes a one
hundred mesh sieve and the balance passes a sixty mesh sieve, the quantity of
asphalt to be added to this powder to produce a mastic would be from twenty to
thirty per centum of the weight of the powder, but where the powder is not of such.
fineness, the quantity of asphalt may run any where from fifteen to twenty-five
The finer the powder the better the mastic in quality, and the purer
the asphalt the better the result and the less percentage used.
per centum.
The simple lime-rock powder makes a good mastic, since by this process the.
quantity of asphalt it contains can be regulated to nicety.
There can be no fixed proportions given for making mastic, as it all depends upon
the degree of purity of the asphalt and the degree of comminution of the powder.
The purer the asphalt the less of it is required to make the mastic.
rock-powder the more asphalt it takes.
The finer the
The simple direction for making mastic is, add asphalt to the rock powder
until the mass becomes plastic enough to spread when it is hot, the less asphalt
when this point has been reached the better for the wear of the mastic in use.
It will also be understood that carbonate of lime powder in the form of chalk
may be used if desired in place of rock-powder, but the latter is preferable.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The herein described asphaltic composition powder for roadways, produced
by the combination and mixture of carbonate of lime rock powder with or without
the addition of sand or other stone powder, with asphalt rendered fluid by a
solvent, the said solvent being subsequently recovered as vapor and the mixture
so freed from solvent subjected to heat to solidify and increase the adhesive
qualities of the asphalt upon the powder particles; the said rock powder being of
a fine grade and a coarse grade, the former exceeding in weight that of the latter

page_text: grade, and producing when treated as described an asphaltic carbonate of lime
in powder or in mastic form whose constituents shall be substantially identical
with those of the natural asphaltic carbonate of lime rock powder known as
Neufchatel.
2. The process herein described of producing in powder or in mastic condition
for roadways, an asphaltic composition in which the powder of asphaltic lime rock
is mixed with fluid asphalt in the way and in the proportions substantially as herein
described.
Dated this 6th day of February 1901
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.