Evening star. [volume] (Washington, D.C.) 1854-1972, 1916-07-09
WHAT THE GOVERNMENT Is DOING

members that vary as much as zoo
or 800 per cent in strength.
In the case Of structural steel-the
great rival of and yet co-operator with
concrete-the material is used for
building just as it comes from the
plant and can, of course, be standard
ICED easily. Cement, which Is the
basis Of concrete. is made and tested
with considerable care, it is true. but
the character of the concrete which Is
determined from the factory tests than
the quality of steel could be found from
tests applied to the crude iron ore
from which 1t is made.
Besides cement. sand, gravel or stone
and water enter into the making of
Of the solid Ingredients, the proportions
Of both solids and liquids and the
methods of mixing and handling that
the quality of the finished product de-
pends Since the sands and gravels
available in different parts of the coun-
try and even in different neighoor-
hoods. vary widely, 1t is not strange.
bureau of standards experts say, that
such wide ranges are found In the
strength and wearing qualities OF con-
crete structures in different localltles
In order that it might be in position
to offer valuable suggestions Tor I'M
proving the quality OF the work IN
what is one Of the most important In.
dustries in the country. the bureau OF
standards has recently carried out ek-
tensive experiments by varying the
many factors that enter into the prep
aration of concrete, and testing at sew
eral ages blocks and cylinders molded
from the different mixtures. Much in
formation has been secured which is
Of great interest to contractors. build
ers. engineers, proprietors and even to
. the householder in city and country
who may wish to use concrete on
small scale. One interesting fact
brought out Is that the proportion OF
water used in mixing is Of vital conse-
quence, "slush mixtures" turning out to
be strikingly weaker than "quaking
or "mushy" mixtures on every test with
other factors varied in different ways.
The difference in strength ranged from
800 to 275 per cent.
The establishing of this fact is of
vital concern to the building trade be-
cause of the growing movement to dis
tribute concrete on job in long chutes
from a central tower. According to
the showings made in the bureau OF
standards tests the contractor who uses
the sitter and carefully prepared mix
lures of concrete and delivers this ma
terial to the required places by older
methods is probably giving his patron
an incomparably more dependable and
lasting structure than the man who
uses concrete SO fluid that 1T will easily
flow down the chutes at the low gradi-
emit usually employed. The contrast be-
tween the most desirable methods and
those largely in commercial use is made
greater by the fact that though the bu-
reau experts found progressively weak
er concretes as the proportion of water
became greater. they did not go so far
toward fluid mixtures as they have OBJ
served some contractors to do.
Among other matters emphasized by
the experiments is the desirability of
knowing the value for concrete maxi
ing of sands and coarser aggregate.
Some materials apparently like those
Of proved value were found to be
worthless. Actual experiments in the
making and testing of concrete sam
pies is the only wholly satisfactory
way of determining the value of in
gradients. the specialists point out.
With fixed proportions of sand and
coarse aggregate, the government ex
perimenters found. any increase in
the proportion of cement gives
stronger concrete. 1t was also found,
however. that with a fixed proportion
gregate. marked variations in strength
could be brought about by merely
varying the proportions between the
sand and gravel or stone.
Equally important with other factors
in the fabrication of concrete, the ex-
thorough mixing. 1t was found that
exactly similar ingredients mixed by
different workmen gave concretes
varying as much as 10 per cent in
strength.
While concrete making cannot be
standardized because of varying mate
rails. much, the bureau of standards
concludes. can be done to improve its
quality under any conditions The
experts who conducted the recent ex-
periments believe that If a rigid in
spection is carried out of all of the
factors shown by the investiga tons to
be important the compressiye
strengths of most concretes as com
mercially made can be increased from
rs to 400 per cent or even more
More and more the manufacturers of
the United States are learning what the
manufacturers of Eu-
Profits From rope, and especially
Germany. learned many
~ Aouoets. years ago-t that the
paying end of an industry is often it's
by-products. That lesson, which is
being taught largely through the gov
ernment's technical agencies. is prom
Using to solve the recently perplexing
potash problem.
When the European war cut off from
America it's annual supply from Ger
many of s20,000,000 worth of potash,
Germans felt pretty sure that the ship
ments could be resumed again when
peace came, however long the delay
might be. because Germany has a viz
tual monopoly on the worlds potash
stores With the German potash not
available government scientists at first
devoted their whole attention to the at
tempt to find in this country deposits
of natural potash salts. and this gave
German interests no great alarm be-
cause of the known scarcity of such
beds Now, however, the bureau of
mines is finding that there is great
promise of a production of potash as a
by-product from more than one of the
great established industries of the
country. and representatives of the
German potash trust are really coming
to fear for the first time that their best
customers will be lost.
Experts of the bureau of mines first
demonstrated some months ago that
potash In paying quantities can be ex-
tracted by electrical devices from the
fumes issuing from Portland cement
plants. and already numerous cement
establishments in all parts Of the coun-
try are installing the necessary ma
chinery to save this hitherto wasted by
product. There was some question
whether the cement industry would
furnish enough potash for home con-
sumption even il all plants installed the
fume-precipitating devices; but recent
ly the bureau of mines has found that
In another Of our dominant Industries
steel and iron making-tons of priceless
potash are being sent skyward in fumes
from blast furnaces. Experiments In