The herald., 1897-03-26
Designed to Eliminate Every
Chance for Dispute
THE EPARK COMMISSIONERS
THE PRESIDENT ACCEPTS HIS
ELYSIAN PARK MOUNTAIN
Short Session Of the Committee on
Water Supply-Engineer Dock
weiler's Plans Are About
Completed-Notes

AT the meeting of the bOaru OF puDHc
works today City Engineer Dockweiler
will present the new specifications for
asphalt paving. Mr.. Dockweiler, II Will
be remembered, presented specifications
TO the council two or three weeks ago,
which were in turn referred to the board
of public works and came up at the last
meeting, but action was deferred. In the
meantime Mr.. Dockweiler has been in
correspondence with asphalt experts and
also followed closely the proceedings in
the Main street investigation. He also
took advantage of the visit of Prof. Price.
the San Francisco expert, to gain some
valuable information. AS result of all
this Mr. Dockweiler has thought it best
TO make several alterations in the specifi-
cations as previously submitted. He
SAYS that he wishes TO get up set or
standard specifications. covering every
point that can possibly be raised, and
yet leaving the field open for competitive
bidding. This, he believes, he has now
accomplished and he will ask the board
to recommend TO the council their adop-
tion. 1t is probable that there will be
representatives of the various asphalt
companies before the board, and Mr..
Dockweiler will also be In attendance.
California, Mr.. Dockweiler says, has the
best asphalt in the world, and for this
reason that material is specifically
named. This will not create monopoly,
he says, as there are numerous mines to
select from and several establishments
which furnish liquid asphalt AS this Is
inu 10 n
terests. the proposed specifications are
given in full. as follows:
Upon the foundation prepared as speci-
fed there shall be spread and construct
ed a layer of asphalt wearing surface
two inches in thickness after rolling,
which shall be composed by weight as
follows:
Refined asphaltic cement IA to II per
cent; sand, SO to 70 per cent; powdered
carbonate of lime or mineral dust to
s per cent.
The finished pavement or asphalt
wearing surface must show on analysis
not less than II 80 per cent bitumen So
luble in chemically pure carbon di sui
phide, which bitumen must not contain
over 80 per cent of its weight insoluble
in petroleum ether Cor light gasoline) of
a gravity of 0650 to O700.
The btumen soluble in carbon di sui
phide must not be brittle, but must be
firm, elastic and cohesive at tempera-
lures varying from 40 to so degrees
Fahrenheit; between so and 80 degrees
Fahrenheit it must still retain consid-
cradle elasticity and cohesiveness; from
80 to 100 degrees Fahrenheit it must not
become too soft and must still have
elasticity and cohesiveness.
The powdered carbonate of lime or
mineral dust must be of such degree
Of bo+ atx-,o ,o1 Of xt-fIr
through a thirty-mesh screen, and a.
least 20 per cent shall pass through
hundred-mesh screen. The mineral dust
must be of such nature as not to be af-
fected by water.
The sand must be clean, sharp, washed
sand, free from clay or loan, of such
size that the whole of 1t will pass through
a ten-mesh screen, and between to II per
cent shall pass through a hundred mesh
screen, and shall not contain over 5 per
cent alumina, sulphate of lime and oxide
of iron.
The aephaltic cement shall be COM
posed of refined natural California solid
asphalt and refined natural California
liquid asphalt, unmixedwith any of the
products Of cold tar, residuum of petro-
leum oil or any other inferior btumn-
Gus materials of any kind. The use of
artificial asphalts or bitumens is ex-
pressly prohibited.
The natural solid asphalt used in the
composition of the asphaltic paving ce-
ment shall be free from all deleterious
substances, such as non-bituminous or
ganic matter soluble salts, clay or loam.
The refined natural liquid asphalt shall
contain not less than 9s per cent BIZ
tumen, soluble in chemically pure car
bon di sulphide. Its flash point shall not
be less than 300 degrees Fahrenheit, and
its acidity in terms of caustic potash
shall not exceed per cent.
The paving cement formed of the nat
ural solid and the natural liquid asphalt
shall contain SO per cent of bituminous
matter, soluble in chemically pure car
bon di sulphide, which bitumen must
not contain over 30 per cent of it's weight,
1nsoluble in petroleum ether (or light
Easoline) of a gravity of 0.650 to 070O. 1t
shall be free from water and all deleteri-
Gus substances. 1t shall be of fine and
uniform composition and shall contain
nothing that will vaporiZe below a tenn
perature of 800 degrees Fahrenheit un-
der ordinary treatment.
The sand and asphaltic cement shall be
heated separately to about 300 degrees
Fahrenheit. The powdered carbonate of
lime or mineral dust, while cold, Shall
be mixed with the hot sand in the re-
quired proportione, and then mixed with
the asphaltlc cement at the required
temperature in suitable electric or
hydraulic or steam power mixer that
VIII effect perfect mixture of all of the
ingredients of the asphaltic wearing sur
face.
The proportion of pulverized carbonate
OF lime or mineral dust shall be varied
according to the size Of the sand so as
to properly fill the void spaces between
the sand.
The amount of asphaltic cement used
within the above specified nercentapa
shall be such that after the asphaltic
pavement layer has received its ut
most compression. the voids between
the sand and particles of limestone or
mineral dust shall be completely filled
with asphaltic cement, and no more as
phalt shall be present than may be nee
essary to secure this result.
The heat in refining the asphaltic ma
terials and in the preparation of the
wearing surface shall he 50 annlied q G