Evening star. [volume] (Washington, D.C.) 1854-1972, 1904-06-08
MAKING PORTLAND CEMENT.
A Great Industry Of Eastern Pennsyl-
= vania That Has It's Romance.

| From the New York Sum
YES" said the. mechanical engineer
"there is more d1 romance In making Port
land cement than you would expect. OF
course. I'm right here In the mill all the
time, but I've hAds an exciting winter, for
| all that.
We've had several floods and a fire in
| the shops. FveThad to do Washington
| stunt Of crossing the Delaware through
| the ice a numbeE-of times. Then I've had
one or two bad mixups In the machinery,
and row with the Hinks'-our Hungarian
1 laborers. Oh. YES; ysu don't have to get
| into the Jap war to find excitement There
are mighty few people who understand just
what Portland cement is and know how
many its uses are. Everybody knows that
| 1t is used for walks. and the foundations
| of buildings. but there are many other uses.
| In the first place. enormous quantities of
cement are used by railroads. for bridge
piers and culverts. The railroads have also
begun to use IL for ties; fence posts have
been made of 1T. too. Walls in Notifications
have been built of the cement, and 1t is
made up In the form OF building blocks
hollow, and therefore very light. yet as
strong as the old-time solid block OF stone.
The most curious use OF It, though, Is in
ships-as a lining to the steel she'll Of the
hull.
Now. I'll just tell you what the cement
is and show you how it Is prepared. The
foundation is limestone. with certain pro-
portion-of course each firm has its own
formula, which Is a trade secret-of mag
nesia and silicates. There are great beds
of limestone In this region. We have our
own quarry right at hand, which supplies
all we can use The rock. as 1t comes from
the quarry. is first crushed in large roller.
which reduces 1t to the size Of the lower
dressing in a macadam road. Leaving this
first roller. 1t is carried on by chain of
buckets to another, where 1t goes through
the process known as balling..
I'm this roller there are placed a number
of iron balls. each weighing twenty pounds
and about TONS weight of them to the
crusher. BY this process the stone is ground
to about the size Of granulated sugar. The
other materials are then added to the
crushed limestone
1.-The next step Is the baking, which Is
done in long rotary kilns As soon as the
burning reaches the proper stage. the
clinkers. Of dark green color. are carried
on by the bucket chain to the tube roller.
where the final grinding produces a fine
powder. In this last stage the heavy balls
used in the second roller are replaced by
pebbles, which have to be frequently re-
newed.
During the process Of manufacture 1t Is
repeatedly tested. The first test Is the
chemical one. to insure the correct combina-
ton Of ingredients. Then there are the me-
chanical tests. for strength and durability.
The powder should be sufficiently fine to
pass through sieve with 10000 meshes to
the square inch; and there are requirements
which 1t must meet as to the time taken
in setting and for tensile strength-the
power to resist various strains to which 1t
may be subjected when in actual structural
use. The peculiar property of Portland ce-
ment that makes it OF great value to build
ers Is its quality Of growing continually
harder and stronger in USE
THE Importance of Portland cement as
an article of commerce Is much greater
than is commonly understood. In 1860
10 fryy fa ofJr I,or n1o
France produces annually about 5000. 600
barrels. and England 100000. while Ger
many leads with a yearly output of some
20OO0.0OO barrels, The industry Is con-
stantly increasing, both in the amount of
production and Ia it's value new uses
are developed A very large plant was es-
tablished not long ago In New South Wales.
under the direction Of a German expert, and
has been doing an extensive business. In
these countries chalk is generally used, in
stead of the limestone that is worked in the
Pennsylvania mills and the process Of man
ufacture varies In certain minor details