Re: Ferrocement submarine

[DaveIrons@aol.com]

Re:EdwMullin@aol.com

Ed

Most of the research in concrete pressure hulls has been on un-
reinforced concrete.  The hulls with internal steel reinforcement
failed at lower pressures than the un-reinforced hulls.  More
alarmingly the reinforced hulls failed unpredictably.

In the Seacon project, a full sized habitat was built with steel
reinforcement.  The design rational for using steel reinforcement
was not explained.  The habitat was a successfully tested but never
manned.

Testing a ferrocement or concrete hulls has been a problem in the
past.  There was no way to tell if a ferrocement boat was properly
constructed.  Often ferrocement boats had internal problems that
could not be detected.

However, I recently saw a program on the Discovery channel. 
They were using computers and sonic sensors to map out fossils in
solid rock.  The technique reminds me of the ultrasound pictures of
babies while still in womb.  I think the equipment could be adapted
to concrete pressure hulls.  Ultrasound equipment detects
differences in density.  A void in a concrete hull would found using
ultrasound equipment.  The void could be repaired using polymer
reinforced concrete.  The repaired section would have twice the
strength of the concrete hull.

With the rapid drop in computer and electronic equipment this type
of test may soon be affordable.  Or perhaps some nice
Paleontologist might lend us his equipment.

I built a garden pond out of ferrocement about ten years ago.  I
would estimate that it takes about ten times the number of hours
that conventional formed concrete would take.

David Irons