[PSUBS-MAILIST] concrete

[hank pronk]

Marc,
Not only is it dirt cheap, concrete is so easy to form. The material cost for a 6 foot sphere is in the hundreds, not thousands. Hank
--------------------------------------------
On Fri, 4/11/14, Marc de Piolenc <piolenc at archivale.com> wrote:

 Subject: Re: [PSUBS-MAILIST] concrete
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Friday, April 11, 2014, 8:26 PM
 
 I don't have hard numbers, but
 remember that resistance to mostly 
 compressive loading is a structural STABILITY problem. Most
 practical 
 steel structures buckle under compression long before
 reaching their 
 actual compression limit. Concrete has an advantage there
 due to its 
 stiffness - the NCEL tests suggest that it comes much closer
 to using 
 its full compressive strength.
 
 That said, my primary interest in concrete is due to its
 cost and ease 
 of maintenance.
 
 Marc
 
 PS. If anybody is interested, I will add the relevant
 reports that I 
 have to my public Dropbox folder and post the link.
 
 On 4/12/2014 3:15 AM, hank pronk wrote:
 > A six foot od sphere built in 1.25in thick steel would
 be equal in weight to 4in thick concrete.  I would not
 ever expect 4in concrete to compare to 1.25 steel. 
 But, it would be interesting to know where the concrete
 stands in comparison.
 > Hank
 > --------------------------------------------
 > On Fri, 4/11/14, Marc de Piolenc <piolenc at archivale.com>
 wrote:
 >
 >   Subject: Re: [PSUBS-MAILIST] concrete
 >   To: "Personal Submersibles General
 Discussion" <personal_submersibles at psubs.org>
 >   Received: Friday, April 11, 2014, 9:59
 AM
 >
 >   A huge amount of work was done on
 >   concrete for pressure-resisting
 structures, including long
 >   term, deep exposure tests, by the US
 Naval Civil Engineering
 >   Laboratory. Most of the reports are
 available for
 >   downloading free of charge from DTIC.
 >
 >   Excellent results were achieved with
 concrete having NO
 >   reinforcement. There has been limited
 work done with
 >   prestressed concrete and even less
 done with reinforced
 >   concrete and ferrocement, which can
 reasonably be expected
 >   to give much more efficient and
 distortion-tolerant
 >   structures.
 >
 >   Marc
 >
 >   On 4/11/2014 8:25 PM, hank pronk
 wrote:
 >   > A cheap alternative to a super
 strong sphere hull is
 >   re-enforced concrete. I feel like
 hiding under a blanket
 >   while I say this,lol.  I know it
 is way out there, but
 >   concrete is super strong under
 compression.  It is not
 >   so good for impact resistance. 
 Concrete is a very easy
 >   material to work with and form into a
 sphere shape.  I
 >   have no idea what thickness would be
 needed.  Properly
 >   engineered I would trust it.
 >   > Hank
 >   >
 >   >
 _______________________________________________
 >   > Personal_Submersibles mailing
 list
 >   > Personal_Submersibles at psubs.org
 >   > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
 >   >
 >
 >   -- Archivale catalog: http://www.archivale.com/catalog
 >   Polymath weblog: http://www.archivale.com/weblog
 >   Translations (ProZ profile): http://www.proz.com/profile/639380
 >   Translations (BeWords profile): http://www.bewords.com/Marc-dePiolenc
 >   Ducted fans: http://massflow.archivale.com/
 >   _______________________________________________
 >   Personal_Submersibles mailing list
 >   Personal_Submersibles at psubs.org
 >   http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
 >
 >
 > _______________________________________________
 > Personal_Submersibles mailing list
 > Personal_Submersibles at psubs.org
 > http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
 >
 
 -- 
 Archivale catalog: http://www.archivale.com/catalog
 Polymath weblog: http://www.archivale.com/weblog
 Translations (ProZ profile): http://www.proz.com/profile/639380
 Translations (BeWords profile): http://www.bewords.com/Marc-dePiolenc
 Ducted fans: http://massflow.archivale.com/
 _______________________________________________
 Personal_Submersibles mailing list
 Personal_Submersibles at psubs.org
 http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles