El Paso herald. (El Paso, Tex.) 1901-1931, 1913-08-23

light lines, telephone system, railroad
ward. repair shops, cOrralS, etc. Ihese
plants are completed and all are op-
The power plant was started on July
II, 1911, when ground was broken Tor
the foundations and the power was
turned on to the lines on FeDruary IL
1912 This plant consists or three nor
fzontal steam turbO generators ana
furnishes 1000 horsepower. This plant
is really the heart of the entire work
and since the time power was uIHe 81
on there has been no shut down or
delay.
The sand cement plant is one OF the
unique features As the name implies.
it is used to mix finely ground SAND
rock with raw portland cement The
sand rock is brought in from the quar-
~ and passed through small cruSner
which reduces the rock from about the
size of mans head to pieces ABOUT the
size of a large marble II the SAND
rock is wet, it is passed through a
large cOne-Shaped dryer, made OF boiler
iron, and much like horizontal steam
boiler in appearance, except that one
end is larger than the other, and that
it revOlVeS constantly At the large
end there is a fire box. and at the small
end a smOkesJack- Fire is kept in the
fire box. and the smoke and heat pass
through this long revolving drum IN
which the rock to be dried is tumbhng
about. The cOnical shape OF the drum
large end slowly and drop out on 10
an elevator. The heat passing through
the moving mass Of rock carries or
the moisture
Treatment Of the Rock.
If the rock as it comes from the
crusher is dry, it passes by the dryer
In either case the crushed rock IS ell
evated to a bin high in the roof OF the
building, from which it is fed to the
ball mill This is another big revoly-
ing boiler plate cylinder filled with
steel balls. The balls beat and grind
on one another, and catching the rock
fine, clean sand which "nen
fine enough. is sifted out by ,
screens and elevated to another bin I
in the top Of the building This pin is
about 80 feet long, and is divided into
two compartments, one of which holds /
the sand and the other the ordinary /
commercial cement which comes IN on |
the railroad close by.
Sand and cement are drawn OH from !
this double bin to a "blender," which Is I
a very simple little machine whose |
duty it is to select the right amount }
Of sand and cement from the quantity (
fed it. and deliver the mixture to a 4
third elevator which raises it into bins /
over the tube mills.
Mixing the Concrete.
There are four Of these tube mills, I
arranged side by side. Each one is a
boiler plate cylinder five feet in diam :
eter and p feet long, and Is reVoIVed !
on its axis by an 50 horsepower motor
This cylinder is about half filled with I
smooth, round, or egg-shaped peDDles
that tumble over and over and ruD on !
one another, similar to the steel ballS
in the ball mill. The mixture of sand /
and cement is fed into this mass OF /
tumbling pebbles. and before 1t gets out
at the other end it has been beaten,
battered and ground until the tlneSI
dust in the roads is coarse beside II
This dust is the product sand cement
1t is kept in the tube mill until 90
percent of it viii pass through zVV
mesh screen, a screen so line tnat II
looks like gauze This product AFTER
{ energies from the tube mill, IS con-
yeyed to a big storage bin, and atter
4 few days aging is ready for use IN the
concrete. The capacity of the planI
running full blast, is about 20 barreIs
Der hour.
Advantages of Sand Cement.
Sand cement is comparatively new
n use. although il has been known Tor
4 long time. ana has many advantages
over Portland cement. 1t develops It's
strength slower than Portland cement
in technical terms. "sets" slower. and
Is a result does not require so much
are in handling. 1t gives off little
leat in setting. and consequent
y sand cement concrete does !
lot tend to contract and crack to the I
extent that ordinary concrete does. Its |
inal strength, when properly proper