<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body><div>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 :)</div><div>Thanks,</div><div>Scott Waters</div><div><br></div><div><br></div><div><br></div><div><br></div><div><div style="font-size:75%;color:#575757">Sent from my U.S. Cellular© Smartphone</div></div> <br>Joe Perkel <josephperkel@yahoo.com> wrote:<br><table cellspacing="0" cellpadding="0" border="0"><tbody><tr><td valign="top">It seems to me that with reduced cost materials there is a tendency to go big and unwieldy. <br>Wasn't that the case with that one fellows concrete sub yacht? It's on the bottom of a lake somewhere if I recall.<br><br><br>Joe<a href="http://overview.mail.yahoo.com?.src=iOS"><br><br>Sent from Yahoo Mail for iPad</a></td></tr></tbody></table> <div id="_origMsg_">
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<span style="font-weight:bold">From:</span>
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Sean T. Stevenson <cast55@telus.net>; <br>
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<span style="font-weight:bold">To:</span>
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Personal Submersibles General Discussion <personal_submersibles@psubs.org>; <br>
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<span style="font-weight:bold">Subject:</span>
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Re: [PSUBS-MAILIST] concrete <br>
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<span style="font-weight:bold">Sent:</span>
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Sun, Apr 13, 2014 6:16:35 AM <br>
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<div class="moz-cite-prefix">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:<br clear="none">
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<img src="cid:_com_android_email_attachmentprovider_1_1511_RAW@sec.galaxytab" alt=""><br clear="none">
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On 2014-04-12 21:52, Marc de Piolenc wrote:<br clear="none">
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<blockquote type="cite">I
had forgotten about the lubricant/plasticizer properties of fly
ash.
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Marc
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On 4/13/2014 10:55 AM, hank pronk wrote:
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<blockquote type="cite">Marc,
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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"
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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.
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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
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Hank
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On Sat, 4/12/14, Marc de Piolenc <a rel="nofollow" shape="rect" class="moz-txt-link-rfc2396E" ymailto="mailto:piolenc@archivale.com" target="_blank" href="javascript:return"><piolenc@archivale.com></a>
wrote:
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Subject: Re: [PSUBS-MAILIST] concrete
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To: <a rel="nofollow" shape="rect" class="moz-txt-link-abbreviated" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="javascript:return">personal_submersibles@psubs.org</a>
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Received: Saturday, April 12, 2014, 10:40 PM
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Actually, all else being equal, using
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only fine aggregate (sand) will give a stronger mix. Coarse
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aggregate is needed mainly to make the mix affordable - as
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bulk filler, in other words - and also for decorative effect
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in some applications where the fresh concrete is brushed to
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show off the aggregate.
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You have to be careful, in very high-strength applications,
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to make sure that the coarse aggregate is chemically inert
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with respect to the cement matrix. Some siliceous aggregate
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will weaken the concrete in the long term by reacting slowly
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with the matrix long after cure.
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Confusingly, very fine silica incorporated in the form of
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fly ash, rice husk ash or silica fume can give a
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super-HIGH-strength mix. The reason for the effect is that
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the very fine silica reacts with the alkali formed DURING
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cure and actually strengthens the cement matrix.
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Unfortunately, much of the fly-ash and volcanic ash cement
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on the market is too coarsely ground to harness this
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effect.
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Best,
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Marc de Piolenc
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Ferrocement freak
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