Evening star. [volume] (Washington, D.C.) 1854-1972, 1910-05-21
STRENGTH Of MATERIALS
RESULTS OF TESTS SHOWN AT
THE BUILDERS EXCHANGE.
Comparison of Shale Clay, Marble,
Sandstone, Concrete, Cement Nor
tar and Neat Cement.

An interesting collection of specimens OF
building materials. tested by the struc-
tural materials laboratories OF the United
States geological survey, Is now on view
at the Builders Exchange on II street.
near 18th. There are shown wire cables
which have been strained to rupture, and
hollow building blocks Of cement mortar
called, improperly, concrete blocks, both
two-piece and one-piece. The latter is
really section of the house wall. and
the former constitutes the exterior and
interior surfaces Of the wall
Various bricks are shown which have
passed through the abrasion test. That
liz. the bricks have been locked in a bat
tier. or iron cylinder, with one and one
half inch cast iron spheres and revolved
for forty-five minutes, when the loss in
weight from the brick is computed
Test pieces OF porcelain for electrical
insulation have been punctured by an
electrical current of A, 100 volts and $1,000
volts.
number of specimens show tests for
permeability, or absorption of water.
There are numerous shearing tests and
some transverse or tensile tests, on
different building materials. Tests by
pyometer for resistance to fire are shown.
though they are not to be compared in
elaborateness with those given in re-
cfHL FOuietm on uIc IeS1SLdnCe OIL
Ing materials.
A comparison of tests for compression
strength, different material. is worth
study. shale clay cylinder, size AZ
inch by inch. was burnt to 1870 degrees
centigrate, equal to 2,246 degrees Fahren-
heit the thermometer most widely used
here). loaded with total of 21O.5OO pounds.
shows ultimate unit stress of 14.225
pounds per square inch.
:, cylinder Of the same dimensions, COM
poShd ri Are c1av h1lrnf al the n
perature. loaded with 12l.05O pounds,
shows an ultimate unit stress of 1887
pounds per square inch.
A 311.s-inch marble cube for compression
test shows an average ultimate unit
strength of 1O,220 pounds per square inch.
A four-inch sandstone cube shows ulti-
mate unit strength Of I,7sO pounds per
square inch.
1900 pounds strength.
An 8-inch by 18-inch concrete cylinder,
compress test, age weeks, made of
crushed granite. graded down from pinch
proportion by volume. l part cement, .
parts sand. 3 parts granite. ultimate load
Ill 500 pounds, shows an ultimate unit
stress Of 2,23O pounds per square inch.
An S-inch by 16-inch concrete cylinder,
compress, age weeks, made of limestone.
graded down from IN inch. proportion
shows a unit stress Of $3.50 pounds per
square inch.
An 8-inch by 16-inch concrete cylinder,
compress. age weeks. crushed limestone,
graded from Nv inch. proportion IL: with
load Of 256.66O pounds, shows unit stress
Of s, 1O6 pounds per square inch.
A 6-inch concrete cube. compress. age
weeks, crushed limestone. graded from y
inch, proportion 1:2:4. with load OF 142, 600
pounds shows a unit stress OF S,943
pounds per square inch.
A 2-inch cube cement mortar compress.
age days, ] part cement. parts Mer-
rfmac river sand, with lead of 5,432
pounds, shows unit strength OF 1858
pounds per square inch.
Pinch cube cement mortar, COM
press, age days, 1.3 part cement, with
load of 9.28S pounds. shows unit strength
of 2.317 pounds per square inch.
A pinch cube cement mortar, compress.
age z days, / part cement, parts Otta-
wa sand. load. 1900 pounds. shows q unit
strength Of $50 pounds.
The same. proportions 1.9. with load Of
A. 68. shows a unit OF Liz pounds
A pinch cube neat cement. load GOOSE
pounds, shows unit strength of 5000
pounds per square inch.
BY careful study builders may be able
to sift out from these figures valuable
conclusions.
1t is evident that caution should. be
used in comparing the strength OF mar
BILE which now shows the maximum Of
strength with . 1.24 concrete, which 40
only four weeks old and shows about one