IMPROVEMENTS IN THE COMPOSITION, PRODUCTION, AND APPLICATION OF BITUMINOUS COMPOUNDS
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by George Clark at the Office
of the Commissioners of Patents, with his Petition, on the 10th
November 1875.
I, GEORGE CLARK, of No. 10, Craven Buildings, Drury Lane, in the
County of Middlesex, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE COMPOSITION, PRODUCTION, AND APPLICATION OF
BITUMINOUS COMPOUNDS," to be as follows:-
This Invention relates to the composition, manufacture, and laying
down or application of bituminous mastic composed of the materials,
and layed down or applied in the proportions and in the manner herein-
after mentioned.
Referring to the Provisional Specification of the Invention for "Im-
provements in the Composition and Manufacture of Bituminous and other
Compounds, and in the Application of such Compounds to Paving and
other Purposes," for which Invention I obtained a Certificate of
Provisional Protection; Numbered 1230, and dated Fifth April,. 1875,
having therein described various mixtures of materials and modes
of manufacture of bituminous compounds, of which asphaltum is the
base, and which I designate as asphaltum mastic. I need not here
describe the principal which constitutes the composition of such

page_text: asphaltum mastic, and I hereby declare that I do not claim as part of
the Invention of which this is the Provisional Specification the use and
mixture of asphaltum with other materials, except with the materials
and in the manner herein-after mentioned and described as the first
improvement.
One of the objects of this Invention is so to adapt the quantities and
proportions of the asphaltum and other materials composing the mastic,
as to the nature and proportions of any of the former to the quantity of
asphaltum in each particular mixture, that, the aforesaid asphaltum
mastic shall be suitable for the particular asphalting work or works to
which such mastic has in every case to be applied. As a general rule
when the mastic is intended to keep out damp or wet, as in case of
foundations or roofing of buildings, the quantity of asphaltum in the
mixture should be proportionably larger, and in other cases, such as for
asphalting roads and pathways for which a harder material is required,
the quantity of asphaltum should be proportionally less. This my said
Invention comprises four improvements or parts, of which the following
is a description:-
First Improvement. From numerous practical experiments in the
inanufacture of asphaltum mastic, and from the execution of 'works
with that material, I have ascertained that the use of carbonate of lime
in the form of chalk, and of silica in the form of sand or grit, is in
many respects objectionable, rendering the combination of those
materials with asphaltum by the methods described or mentioned in the
Provisional Specification of my before-mentioned Invention, Numbered
1230, and dated 5th April, 1875, more or less difficult in execu-
tion, and uncertain in its results, and I have also ascertained that
alumina or clay, slate, and stone, the last containing proportionably a
small quantity of silica, and all these materials in a pulverised state
are well adapted to produce asphaltum mastic of good quality, and
which may be easily worked in manufacturing or laying it down. I
therefore propose to manufacture and produce asphaltum 'mastic by
combining and mixing with asphaltum by the action of heat and the
aid of, solvents such quantities and proportions of the aforesaid
pulverised clay; slate, and stone, as are adapted to any asphalting work
to be executed. I do not absolutely preclude the use of chalk, or sand,
or grit in combination with the aforesaid last mentioned materials, as in
some cases for economy of cost it may be advisable and useful to mix
E

page_text: .
chalk, or sand, or grit with those materials or any of them, but for
special asphalting work for which a mastic combining hardness and
toughness and resistance to the extremes of natural heat and cold are
required. I prefer the combination of asphaltum with clay and slate,
together or separately, and stone. Having indicated the advantages of
asphaltum mastic produced with the materials and in the way just
above mentioned in this my first improvement, I cannot lay down any
absolute rule for the proportions in which clay, or slate, or stone, or
any of them in a pulverised state are to be combined and mixed with
asphaltum for any particular kind of asphalting work, as in each
particular case the proper combination and proportions of the aforesaid
materials will have to be ascertained by careful trials in the manufacture
and laying down of the mastic for the particular work to which it is to

page_text: bitumen the quantity of complete mastic in one hundred parts is
diminished, and that of tempering mastic increased. The production of
the three kinds of asphaltum mastic is to be regulated as follows:-
Solvent mastic is to be composed in one hundred parts of the whole
mixture of five to ten parts of asphaltum, twenty-five to forty parts of
pitch, and twenty-five to forty parts of carbonate of lime, and and twenty
to thirty parts of silica, the quantity of each kind of material should be
'so adjusted the forty to fifty per cent. should consist of asphaltum and
pitch, and the remaining sixty or fifty parts, half of carbonate of lime
and half of silica, with the addition of two to five per cent. of liquid
solvent to render the blocks of the compound when cast in moulds as
above mentioned easily soluble by heat, and suitable to facilitate the
melting of the blocks of complete mastic. The composition of the
complete mastic for every one hundred parts should consist of fifteen to
twenty-five parts of asphaltum, two to ten parts of pitch, and of the
remaining parts two-thirds of carbonate of lime and one third of silica.
The tempering mastic should in one hundred parts be composed of five
to ten parts of pitch, ten to fifteen parts of asphaltum, and the remaining
parts of about one-third carbonate of lime and two-thirds of silica.
In the composition of the said three kinds of mastic it is to be under-
stood that in using the terms carbonate of lime and silica it is not
intended that those materials are necessarily to be in the form of pure
carbonate of lime such as chalk, or of pure silica such as sand, grit, or
crushed flint, but that the said substances, carbonate of lime and silica,
may form parts of stone or other compound substances composed of
carbonate of lime and silica, and in many cases it will be advantageous
to substitute clay or slate for carbonate of lime. In the formation of
these three kinds of mastic, as well in the composition of asphaltum
mastic generally, all the substances herein-before mentioned are to be in
a pulverised state. The liquid solvents above referred to may be dead
or green oil of tar, Stockholm tar, petroleum, or petroleum resideum,
but I prefer a mixture of the two first named in about equal pro-

page_text: No. 1230, and dated Fifth April, 1875, I compose the said mastic
of a mixture of asphaltum, clay, or slate, and crushed stone, partly
pulverised and partly in small angular pieces not exceeding one-half
inch to one inch in length or breadth, and in order to thoroughly
incorporate the materials constituting this kind of mastic I,mix the
pulverised and crushed stone with some asphaltum and pitch in a heated
state, and cast the heated compound into moulds, thus forming blocks
ready to be added in the heating pot to solvent and complete mastic as
or in lieu of tempering mastic.
Fourth Improv*.-This consists of the formation of a concrete or
cement foundation on which to lay down or apply asphaltum or
other bituminous mastic for paving or other purposes in the following
manner :-After levelling the ground over which the bituminous
compound has to be applied I first lay down a concrete four to six inches
thick, composed of broken stone or other coarse road material, and
lime or cement in the proper proportions, which are well known, to
form a solid bed. When this bed of concrete is dry and hard I lay
over it planks about half an inch thick and nine inches wide, in con-
venient lengths, say, nine to twelve feet, breaking joint at the ends, and
placed in rows, the planks two to four inches apart from each other.
Over and on the planks thus placed I lay down a coating of fine concrete
one to two inches thick, and composed of lime or Portland cement, the
latter by preference, and sand. This fine concrete is to be filled into the
spaces between the aforesaid planks and floated to a level over the planks.
With reference to the use of asphaltum as the base of asphaltum mastic
in all the compounds and mixtures herein-before mentioned, it is to be
understood that the asphaltum referred to is assumed to contain seventy-
five to eighty per cent. of pure mineral bitumen, so that if the
asphaltum used in any such mixture should contain more or less than
seventy-five to eighty per cent.of such pure mineral bitumen, the
quantity of asphaltum in each of such mixtures will have to be pro-
portionately increased or diminished.