[PSUBS-MAILIST] concrete

hank pronk hanker_20032000 at yahoo.ca
Sat Apr 12 22:55:29 EDT 2014


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
 
 On 4/13/2014 8:58 AM, hank pronk wrote:
 > Marc,
 > If I am not mistaken, the strongest concrete mix uses
 3/4in fractured rock with sand, Portland and water.  I
 would think a sand mix without rock  would not be as
 strong.  Also think of the skill you would need to
 trowel a sphere.  Anyways it is pretty crazy what Sean
 has shown us with the calculations.
 > 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,
 5:58 AM
 > 
 >   I never thought of it quite that way.
 >   Sheesh, that makes concrete boat
 >   advocacy look almost...well, normal.
 > 
 >   Marc
 > 
 >   On 4/12/2014 2:21 PM, Alan James
 wrote:
 >   > Marc,
 >   >>>Right now I feel like I'm
 one of a tiny deviant
 >   cult .......
 >   >     Well you
 are an American of
 >   French heritage hiding away on an
 obscure
 >   > seldom visited South East Asian
 Island populated by man
 >   hungry women
 >   > & Moslem rebels.
 >   > Alan
 >   >
 >   >
 >   ------------------------------------------------------------------------
 >   > *From:* Marc de Piolenc <piolenc at archivale.com>
 >   > *To:* personal_submersibles at psubs.org
 >   > *Sent:* Saturday, April 12, 2014
 1:42 PM
 >   > *Subject:* Re: [PSUBS-MAILIST]
 concrete
 >   >
 >   > I think I will post those reports
 to Dropbox.
 >   >
 >   > Right now I feel like I'm one of
 a tiny deviant cult of
 >   Portland cement
 >   > cultists within the psubs
 community. Maybe the reports
 >   will help me
 >   > proselytize new adherents...
 >   >
 >   > Marc
 >   >
 >   > On 4/12/2014 9:03 AM, hank pronk
 wrote:
 >   >  > 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
 >   > <mailto:piolenc at archivale.com>>
 >   wrote:
 >   >  >
 >   >  >  Subject: Re:
 [PSUBS-MAILIST] concrete
 >   >  >  To: "Personal
 Submersibles General
 >   Discussion"
 >   > <personal_submersibles at psubs.org
 >   <mailto: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
 >   > <mailto:piolenc at archivale.com>>
 >   >  >  wrote:
 >   >  >  >
 >   >  >  > 
 Subject: Re:
 >   [PSUBS-MAILIST] concrete
 >   >  >  >  To:
 "Personal Submersibles
 >   General
 >   >  >  Discussion"
 <personal_submersibles at psubs.org
 >   > <mailto: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
 >   >  >  >  >
 >   >  >  >  >
 >   >  >
 >   _______________________________________________
 >   >  >  >  >
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 >   >  >  >  >
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 >   >  >  >  >
 >   >  >  >
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 >   >  >  > 
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