Re: [PSUBS-MAILIST] Prestressed concrete pipe

[Marc de Piolenc <piolenc@archivale.com>]

I guess everybody thinks of concrete as being brittle.

Brittleness should not be a problem for prestressed concrete; in fact, 
it should be extremely tough. Remember, here is a material all of which 
is under compressive prestress that prevents tensile stress from 
appearing in the concrete matrix at ANY point (if the loads and 
prestress have been worked out correctly) at any time. How then would a 
crack start? And if a crack can't start, it can't propagate.

Prestressed concrete is used in many applications where any tendency 
toward brittleness would be disastrous; bridges, for instance.

Even ordinary ferrocement, with no preload, has shown itself to be very 
tough. The book Concrete Boatbuilding has a good collection of pictures 
of FC boats that were hit by other, mostly larger boats and suffered 
minor damage which was repaired without even hauling them out. One 
motorboat suffered a gas explosion that blew off the entire (wood) 
superstructure and left the hull intact, ready for a new deck and cabin.

Marc de Piolenc

On 3/17/2010 11:37 PM, ShellyDalg@aol.com wrote:
> In a message dated 3/17/2010 8:24:38 A.M. Pacific Daylight Time,
> ojaivalleybeefarm@dslextreme.com writes:
>
>     making end
>     caps you would have an instant submarine!
>
> I think concrete would make a better "habitat" than a moving submarine.
> With a habitat the pressures would be fairly constant, and impact would
> not be a problem, unless you ran your submarine into it while parking in
> the garage !
> It would be pretty cool to have a submerged "house" at the beach. Maybe
> with a tube walkway to the shore. I can imagine where pre-formed pipe
> would be useful there.
> Frank D.
>
>
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.791 / Virus Database: 271.1.1/2751 - Release Date: 03/17/10 03:33:00



************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003.  Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.

If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
	removeme-personal_submersibles@psubs.org

Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.

PSUBS.ORG
PO Box 53
Weare, NH  03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************