Re: [PSUBS-MAILIST] Concrete submarines

[Michael Edwards <me@sustainkauai.org>]

Greetings Juergen & subbers:

Below is a clip of Wilfrieds (the concrete guru) response to the water tight question.
I am unaware of any other projects in the works, do you know? 

I just bought the cement mixer for ferrocement projects on the farm, but am a long 
way from knowing enough for a pressure hull. I had few additional private post with 
Wilfried but still don't understand his mold method without any pictures.

I think this technology has great promise for submarines. Keep us posted!

Best regards
Michael Edwards

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Subject:  [PSUBS-MAILIST] con
Date: Sun, 28 Sep 2003 20:10:55 -0500 (COT)
From: diagroto@ibague.cetcol.net.co
Reply-To:  personal_submersibles@psubs.org
To:  Personal_Submersibles@psubs.org

Dear D,
Not sure to understand your question completly. In any case this was MASSIVE 
concrete 18cm walls - steel 6mm bars as in normal construction must be in 
middle of wall (at least 2 cm from surface) to avoid rust and take full 
tension.(every construction engineer knows it) NO chicken wire involved !
No construction in LAYERS this is ferrocement (chicken wire) for thinn hulls 
(1-3cm) of yachts. My sub was MASSIVE concrete. Liqid in form and compacted as 
in normal construction.

Of course was it watertight.
You seem to have concerns about concrete in direct contact with seawater. My 
boat had a outer skin of 5mm bitumen (tar) reinforced with glass fiber.
So concrete is not in contact with water under pressure - this is similar in 
dam construction. In deed in dam construction filtration problem is by far 
more severe as you have to connect a dam with rock that is filtering etc. in 
practice all this is managable. Covering a submarine with a waterthight skin 
is quite easy compared to that.

All in all in practice concrete in seawater contact is by far less problematic 
as steel or aluminium in sea water contact. 
Can handle it. Problem of CaCo3 process reverse is more in theory than in 
practice. Oil tanks in north sea, drilling platform underwater struckture all 
in concrete are already in use and never presented problems most of them 
without any coating.

Just make following experiment put a concrete, alu, steel probe (holow shpere) 
in saltwater under pressure during a month.
Will see that concrete will alterate by far less than other materials.


Kind Regards

Wilfried
===========================================================

On Jun 16, 2005, at 1:42 AM, Juergen Guerrero Kommritz wrote:

Hello Psubbers
I am searching some information about concrete for
submarine hulls.  I know at least one submarine was
build with concreteand there were some other projects
on the work.
I want to know if the it is possible to use "normal"
portland concrete for the hull I dont´t know if this
will be enought (water thigth)and it is impermeable 
or if it is better to use an special sealling product
for the outer coating layer.
May be it is better to use a sealling product in all
the concrete mixture?
I only have little experience with concrete (only
portland) building bricks and a small water tank that
was not very impermeable.  
I thank you for any information
Best wishes
Jürgen






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