The Fort Peck press., 1935-03-28

= 'S'o "AN oCto q IOW vi SQeetS.
then a gantry sets another row
on top OF the first and drives ehe
sheets way down to bedrock.
General construction BY Govern
ment forces indicate that prepare
tons for the coming dredging sea-
t son r deing vigorously pushed
S 10 completion. While the ice is
] still IN the river and is of unusual
d thickness. continuation of the pre-
sent favorable weather may cause
it to 90 out before April l.. Ac-
. tive dredging operations will COM
mence as soon as practicable after
l the ice goes out.
Three sections of % inch pipe
line across the dam, totaling $50
feet, were placed during the week.
26,OOO Gu, yds. of dirt are placed
in retaining levees. Trestles we're
built for pipelines over the gravel
toes, pipes were laid over the era-
vel and 3 of the land boosters we're
connected. Pits were dug for anch-
ors to be attached to the booster
cars.
The Government raill Dad hand
led 1881 carloads of freight last
week, of which 1120 cars contained
gravel for the toes of the dam The
aggregate net tonnage which has
been handled over the railroad is
over two million since the Begin
ming of operations less than a year
ago Cement in the amount of IS
carloads was received during the
week. The use of this material at
the diversion tunnels is expected
toincrease during the coming months
The physical testing section of
the laboratory designs the concrete
mixtures used about the project.
The specific alton requirements for
any class of concrete usn4siy cen
tain 3 limiting factors: Cd a min
imum strength at % days; y a
minimum number of bags of cement
per cnbsc yard of concrete; 60 a
maximum amount of water which
may be used with each bag Of
cement. Using these limiting val
ues and the gravel and sand as up
piled on the job. the quantities of
cement, sand, gravel and water are
computed so that. when mixed to.
gether, they should give a concrete
of the required Quality. After the
proportions for a mix have been
tentatively determined, trial patches
of concrete are made to see ii the
consistence is satisfactory. If too
wet or too dry, water is either sub
tracted or added and another trial
batch is made. When the consis-
tency is satisfactory. cylinders are
made and tested at 7 and % days.
The test cylinders of concrete are
6 inches in diameter and II inches
high. Removable sleel molds are
used. The cylinders to be tested
are stored either in damp sand or
moist air until the proper age to be
tested.
The proportions for the concrete
are given 10 the field engineer, If
field conditions Indicate slight de-
from the laboratory proLor-
ions, the neld engineer may make
he desired changes. 1t has been
that such changes do not
vary greatly from the proportions
indicated by the laboratory design
New testing machines of the lat
EST type recently received at the
government laboratory will enable
technical work on concrete to be
carried OIL with greater speed aud
'eliability. These machines are
being set IN place.
Concrete, plain, or reinforced with
;teel bars, is one of the present day
)asic construction msterials. " hen
,ver it is used in large GRANTEES.
t is customary to take sanuples
It frequent intervals for testing
purposes. The purpose of the
eStS is TO ascertain that the oh
being poured for a structure
# any kind has the required mimi
mum strength.