The San Francisco call., 1908-04-26
stanr through the succeeding half
hours
MAKE SEVERE TESTS

stanr through the succeeding half
hours.
MAKE SEVERE TESTS
The building materials were placed
In & sliding panel. which when ar
ranged for the IRE tests formed one
side OF the furnace. In the furnace
gas flames were forced by blast of
air against one side OF the panel. After
two hours the panel was brought from
the furnace and the water turned on
from a hose with q pressure OF SO
pounds TO the square inch
The conditions under which these
tests were made were unusually severe.
and as none OF the materials passed
perfectly il proved & good test for
comparative purposes. The tempera-
lures used would hardly be reached in
an ordinary IRE, but might be in a con-
fagratien-
While these tests are not con-
elusive. being but the beginning Of q
general line OF Investigations" said
Director Smith Of the geological sur
yey. they bring out number OF i'm
portant facts. The brick panels prob
ably withstood the tests better than
any other materials. There were two
lots OF common brick tested-one was
an unused. recently manufactured brick
and the other a brick that had been in
an engine foundation for some years.
The latter seemed TO Withstand the
test better.
Fifty per cent of the new brick
were split, while so 10 20 per cent or
the old bricks were not damaged The
bricks at the back Of the panel were
entirely unaffected The hydraulic
pressed brick stood the test better
than any other material No damage
was apparent whatever after the firing
and before the water was applied. and
although a number Of the bricks
cracked 20 per cent Of them were found
10 be sound after quenching-
STONE BEHAVES WORST
There was apparently little differ
ence IN the strength Of the bricks be-
fore and after firing. The natural
building stones behaved worst OF all
the material tested The almost COM
pIete destruction of these stones pre-
cIudes any comparison between them
The sandstone panel entirely collapsed
soon after the test was started
The testing engineers report that il
was difficult TO determine whether the
concrete made Of limestone. granite.
gravel or cIndeTs sustained the least
damage. Their surfaces were all rather
badly pitted by the FIRE and washed
away BY the stream Of water. The
test was unfair 70 cinder concrete, as
Ele sample OF ClL4eI y as RSNNf ND---
tanning q large percentage Of unburned
coal. which ignited and left the surface
OF the concrete pitted. The granite
concrete probably behaved the best
The damage in no case extended far
into the concrete. probably not more
than one and & half inches The
evidence shows that even at this depth.
the temperature was comparatively low.
The rapid heating Of the face Of the
concrete. while the back remained cool.
caused the concrete TO crack vertt-
csliy for some distance back from the
face
The cracking Of the concrete can be
avoided. Il is believed, by using metal
reinforcement, which would distribute
the effect OF the expansion The tests
also brought out most clearly the low
rate al which the heat travels through
concrete. This is one OF the desirable
qualities n materials intended for fire
proofng purposes.
RICH MoRTARs WORK BETTER
Linen tags which were placed in the
hollow concrete blocks when they were
nodded were found 10 be undamaged
after the fire test In many instances
the hollow blocks split after being
b5ected 70 the fire and water test
u was noticeable that the richer the
mortars used IN these blocks the less
they were affected by the test The
uorIars mixed with the greatest per-
centage Of water gave the best re-
suits The wetter richer mixtures in