Evening star., 1916-05-14
WHAT THE GOVERNMENT Is DOING

BY judicious and scientifically con-
structive "adulteration," Uncle Sam
through the recla-
Powdered Sand nation service, is
f.n saving hundreds Of
of the peoples money in building the
great dams that are making it posi-
BILE to bring under cultivation vast
stretches of former desert The "adul-
teration" consists in the pulverizing of
sand to very fine state and the mix
ing of the powder with portland ce-
ment before the latter is used to make
the concrete used in molding the huge
river barriers.
The process was developed a mum.
Der of years ago, but very little use
was made of it in this country until
the need for vast quantities of cement
ing materials thousands of miles from
regular markets. and the consequent
tremendous cost of portland cement on
the project sites furnished the neces-
sity which spurred the reclamation
service engineers to take advantage
of all practicable economies.
To the layman the mixing of seem
ingly inert substance like pulverized
sand with cement is merely a dilution
which should weaken the cement in
accordance with the proportion added
Strangely enough. however. this is not
the result at all. The blend is practi-
cally new cementing substance with
"a strength little. if any. inferior at
any time after setting to that of ordi-
nary portland cement.
Tests made by the reclamation en-
gineers show that briquettes of the
sand cement, as it is called. with about
equal volumes of ground sand and
months strength of 90 per cent that
of portland cement briquettes of the
same age, and are actually stronger
than portland after three years
In addition. the "adulterated' cement
has certain qualities that are consid-
massive work such as dam construc-
ton. 1t does not set as quickly as
portland cement. and is believed to be
less pervious to water The slower
setting is also believed to make for
the existence of fewer internal stresses
The manufacture of sand cement is
not mere matter of pulverizing the
sand material and mixing it with ce-
ment as purchased. After the two sub
stances are blended they are ground
together in tube mills. which still fur
ther reduces the size of the particles,
making the powder practically impal-
pable. The reduction of the size of the
cement particles, engineers say. in
creases the strength of that ingredient
over its efficiency in the market condi-
ton practically enough to compensate
for any weakening effect which the al
dition of the sand powder might have,
making the doubling of the volume
brought about by the procedure so
much pure gain.
The machinery needed is of the type
in lat MT MIA
and. though expensive, 1t has been
reclamation service it is distinct
which are just drawing to a close at
Elephant Butte dam. across the Rio
Grande in New Mexico. the reclamation
service installed sand cement plant
at cost Of $4,000 but saved quar-
ter of million dollars by the transac-
ton; for the service used in the dam
more than 621 900 barrels of cementing
material, AZ per cent of which was
merely sandstone taken from the adj
joining hills
In the one other big project in which
sand cement has been used-the Arrow :
rock dam. across the Boise river. In
Idaho-the service erected "A sixty
thousand dollar plant and saved about
S24O.nOa. SO good have been the show
ings made on these projects that it is
safe to say that wherever in the future
Uncle Sam is faced with jobs calling
for massive use of concrete and where
cement is high the same plan will be
followed.