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RE: Bullet-proof concrete

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Roger,

I have some recent photos of this structure too, showing the "hits". A
internal steel stair case has numerous "hits" and full penetration holes on
the risers.

Actually the concrete was designed as 3000 psi, but we recently cored some
samples (from the slabs) and it tested at +5,500 psi. The rebar for the
girders was 1" square DEFORMED rebar.

The exterior facade is protected by historic order - the facade "spalls"
will never get repaired. Even recent corrosion-related spalls do not get
repaired, just painted.

There are also hand-dug tunnels (more like trenches) under the suspended
lower floor, where pilots used to run from the once barracks to the air
field. The building is now the Pacific Air Command Headquarters.


Mark Geoghegan
Honolulu, HI

             > -----Original Message-----
             > From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
             > Sent: Friday, January 24, 2003 5:22 AM
             > To: seaint(--nospam--at)seaint.org
             > Subject: Bullet-proof concrete
             >
             >
             > Richard,
             >
             > Visit (or look at photos) from Hickam Field, Hawaii,
             > and see how resistant
             > ordinary concrete is to bullets.
             >
             > Now, remember, this is pre-1941 concrete, probably
             > designed at 2,000 - 2,500
             > psi, and the bullets were probably close to 20 mm
             > fired from machine guns in
             > strafing planes on December 7, 1941.
             >
             > HTH
             >
             > A. Roger Turk, P.E.(Structural)
             > Tucson, Arizona
             >
             > Richard Kipke wrote:
             >
             > . > Is anyone familiar with any research or papers
             > regarding concrete walls
             > . > subjected to rifle fire?  I am designing a
             > pre-cast concrete gate house
             > . > which needs to resist Department of Justice
             > classification Level III as
             > . > stated below:
             >
             > . > 2.5 Type III (Rifles)
             > . > This armor protects against 7.62 mm Full Metal
             > Jacketed (FMJ) bullets
             > . > (U.S. Military
             > . > designation M80), with nominal masses of 9.6 g
             > (148 gr) impacting at a
             > . > minimum velocity of
             > . > 838 m/s (2750 ft/s) or less. It also provides
             > protection against the
             > . > threats mentioned in sections
             > . > 2.1, 2.2, 2.3, and 2.4.
             >
             > . > Right now I have a 5" thick concrete wall and
             > have no feel on how well it
             > . > would do.  Would concrete additives such as
             > steel fiber or poly fiber
             > . > offer additional resistance.  I can probably
             > thicken the wall as needed.
             >
             > . > Any assistance would be appreciated.
             >
             > . > Thanks in advance,
             > . > Rich Kipke, PE
             > . > Earth Tech
             >
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