[PSUBS-MAILIST] concrete

[Marc de Piolenc]

Really - it sank? Mind you, it did have walls 6 inches thick and very 
little freeboard. Any lives lost?

Marc

On 4/13/2014 10:35 PM, Joe Perkel 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 <http://overview.mail.yahoo.com?.src=iOS>
>
>
> ------------------------------------------------------------------------
> *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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