The Duluth rip-saw. [volume] (Duluth, Minn.) 1917-19??, 1922-04-15

generally conceded to be the best yet
written, call for a course of one and
one-half inches.
Attention previously has been called
to the fact that limestone dust will be
used in the surface mixture instead of
Portland cement, the proper ingredient
for lasting results. This use of lime
stone dust certainly is contrary to good
practice and the recommendations OF
the consulting engineer for the Barber
Asphalt Co., which company will fur
nish the asphalt for Superior st.
In the issue of March 4, the Rip-saw
showed that a 50. I'd. of asphalt pave
ment with a binder course one and one
half inch thick, and 2-inch top
course will weigh about 800 pounds, of
which only 35 pounds would be asphalt.
This asphalt, used in paving, is btu
minous substance, the quantity to be
used being determined by the percent
age that is soluble in proper proper
ton of a chemical called earbon-di-
sulphide.
Data on Trinidad Asphalt.
Crude Trinidad asphalt is about SO
per cent soluble in carbon isulphide.
Such asphalts as the California and
Mexican products are about 99.5 per
cent, or more, soluble in carbon disul-
phide.
Refined Trinidad asphalt is much too
hard and entirely unfit for paving until
it has been mixed with certain oils,
called fluxes, for the purpose of soft
ening it. The quantity of Oil neces-
sary to get the desired result depends
good deal on the nature of the oil
used. Much more of a hard oil is re-
auired than of a softer and more fluid
oil.
These fluxing oils are comparatively
cheap and the resulting mixture Of
asphalt and flux, called asphaltic c.
ment, can be very much cheapened by
using large quantities of flux. For
all practical purposes, fluxing oils can
be considered 100 per cent soluble in
carbon-disulphide.
The Duluth specifications for as
phaltic cement, as so kindly furnished
tains an interesting clause, as follows:
"It must contain not less than three
(3) per cent Of non-bituminous matter,
insoluble in carbon disulphide.'
Fluxing Limit Objectionable.
The big objection to that clause is
the limit set on the fluxing material
that may be used. In other words, you
may mix two materials, one of which
has Sc per cent bitumen and the other,
the flux, 100 per cent, but the resulting
mixture must not be more than 81 per
cent bitumen. 1t is but simple mat
ter Of computation to see that, under
this clause, 92.7 per cent of this
asphaltic cement must be flux oil and
the remaining 7.3 per cent must be
Trinidad asphalt, just enough to insure
the job to Messrs. Leahy and Clough at
any price they may have the nerve to
ask, and they have shown that they are
not lacking in that respect.
About three years ago, the Rip-saw
printed the details of a repair bill
which commissioner Farrell allowed in
favor of the General Contracting Co.,
Mr.. Leahy's mother concern. That
bill was allowed as an emergency
ordinance, which stated among other
things that the city had no plant with
which to repair its asphalt pavements;
the streets were represented as being
in very dangerous condition, hence it
was necessary to employ Mr.. Leahy's
company. Needless to say, the prices
allowed were fully double of what they
should have been.
Where's the City's Mixing Plant?
The Rip-saw asked at that time, as
it since has asked, what commissioner
Farrell had done with the municipal
mixing plant, plant put in solely for
the benefit of the contractors in Du-