[PSUBS-MAILIST] concrete

Sun Apr 13 14:20:21 EDT 2014

Scott,
Good point, A concrete sphere sub would need all the penetrations cast in place, then tightened after 28 days with through bolds perhaps.
Hank
--------------------------------------------
On Sun, 4/13/14, swaters <swaters at waters-ks.com> wrote:

 Subject: Re: [PSUBS-MAILIST] concrete
 To: "Personal Submersibles General Discussion" <personal_submersibles at psubs.org>
 Received: Sunday, April 13, 2014, 1:44 PM

 One thing if
 you do decide to try a sub made of concrete, is to be sure
 you cut tru holes with dimond or carbon rather than any kind
 of impaction device (hammer drill). Using a impaction
 weakens the integraty around the hole itself. If you do try
 this, let me know and I can get you all kinds of deals with
 dimond cutting materials through my business. We buy
 thousands of dollars of it every year
 :)Thanks,Scott Waters

 Sent
 from my U.S. Cellular© Smartphone 
 Joe Perkel <josephperkel at yahoo.com> wrote:
 It seems to me that
 with reduced cost materials there is a tendency to go big
 and unwieldy. 
 Wasn't that the case with that one fellows concrete sub
 yacht? It's on the bottom of a lake somewhere if I
 recall.

 Joe

 Sent from Yahoo Mail for iPad 

                                 From:

                             Sean T. Stevenson
 <cast55 at telus.net>;                            

                                 To:

                             Personal Submersibles General
 Discussion <personal_submersibles at psubs.org>;         

                                 Subject:

                             Re: [PSUBS-MAILIST] concrete    

                                 Sent:

                             Sun, Apr 13, 2014 6:16:35 AM    

     I ran that same
 6' diameter 4" shell,
       but using an ultra high-performace concrete with no
 aggregate, but
       with steel fiber reinforcement.  Working pressure
 came out to more
       than 1700 m.  That said, while the compressive
 strength of this
       stuff is 160 MPa, the tensile is only 8 MPa, so you
 absolutely
       have to avoid putting this stuff in tension. 
 Sphere may not be an
       issue, but a cylindrical hull would probably require
 some sort of
       pretensioned reinforcement.  Results:

       On 2014-04-12 21:52, Marc de Piolenc wrote:

     I
       had forgotten about the lubricant/plasticizer
 properties of fly
       ash.

       Marc

       On 4/13/2014 10:55 AM, hank pronk wrote:

       Marc,

         We don't get segregation at all, when pumping it
 we fill the
         wall and then let it flow, I call it "ride the
 wave"

         Also pumping the concrete helps hold the concrete
 together, it
         stays in a cylinder shape until it hits the wave. We
 must use
         fly ash because the aggregate and sand is washed so
 well there
         are no fines left.  The jagged sand won't
 flow through the
         hose.  Fly ash is like little ball bearings and
 makes it flow
         through the hose.  These are the things that
 make me think a
         mold  is the way to go.  Four inches wall
 thickness would be a
         breeze for this mix.

         That makes sense that the rock is a cheap
 filler.  I would still
         use the pea gravel mix, I have made a test panel and
 I drove my
         bob-cat over a 2in thick 4by4 panel with no
 breakage.  I know,
         very scientific .lol

         Hank

         --------------------------------------------

         On Sat, 4/12/14, Marc de Piolenc <piolenc at archivale.com>
         wrote:

           Subject: Re: [PSUBS-MAILIST] concrete

           To: personal_submersibles at psubs.org

           Received: Saturday, April 12, 2014, 10:40 PM

           Actually, all else being equal, using

           only fine aggregate (sand) will give a
 stronger mix. Coarse

           aggregate is needed mainly to make the mix
 affordable - as

           bulk filler, in other words - and also for
 decorative effect

           in some applications where the fresh concrete
 is brushed to

           show off the aggregate.

           You have to be careful, in very high-strength
 applications,

           to make sure that the coarse aggregate is
 chemically inert

           with respect to the cement matrix. Some
 siliceous aggregate

           will weaken the concrete in the long term by
 reacting slowly

           with the matrix long after cure.

           Confusingly, very fine silica incorporated in
 the form of

           fly ash, rice husk ash or silica fume can
 give a

           super-HIGH-strength mix. The reason for the
 effect is that

           the very fine silica reacts with the alkali
 formed DURING

           cure and actually strengthens the cement
 matrix.

           Unfortunately, much of the fly-ash and
 volcanic ash cement

           on the market is too coarsely ground to
 harness this

           effect.

           Best,

           Marc de Piolenc

           Ferrocement freak

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