Would you be so kind as to come back from July and into
June with the rest of us?
Finn,
I would use plywood forms secured at the corners, you also need
bolts
through tubes at regular intervals throughout, with good sized
washers under
those bolt heads. The tubes themselves act as spacers and
could be secured
to the reinforcing bars so as to secure the form position
however you would
also need to secure the base somehow so that it didn't
move around as well
as some timber braces to maintain the top
position.
If it were me I would do a metre at a time and use
the top tube holes after
the concrete has set, as the new bottom
form holes.
Leave the top rough so as the new concrete has something to
bite into - if
you use a concrete vibrator don't do it too much as the
larger stones
migrate to the bottom and weaken the structure, just enough
to get out any
cavities ( bubbles)i.e. half a minute. My figures ( by
memory) indicate
about a ton per cubic metre.
George (down
under)
> Finn, I have designed concrete forms in my day
> job,
however they were of a different variety
> compared to what your
doing.
> [Metal pre-cast forms for man holes, city sew
> systems
and various "under Street" concrete
> structures]
>
> It
would seem to me that your major problem is
> going to be hydraulic
pressure at the bottom of
> the form.
> If concrete weigh's
150lb's per cubic foot 16" x
> 16" x 104"=26624/1728=15.4 cubic feet or
2311 lb's
> of concrete.
> Now if my numbers are right you should
be dealing
> w/ 9.0 PSI pressure around the form at 1"
>
elevation.
> I don't think just plywood is going to cut it..
> if
you strapped the bottom circ. w/ 2 x 4 and
> then the
following elevations
> [ all measured from Datum= bottom of
colum]
>
> 3"
> 6"
> 9"
> 12"
>
15"
> 18"
> 21"
> 25"
> 29"
> 33"
>
37"
> 42"
> 47"
> 52"
> 58"
> 64"
>
72"
> 82"
> 104"
>
> All elevations should be strapped
by a 2 x 4 [23"
> lng + 2x plywood thickness]around the circ.
[2"
> high x 4" out from the form]
>
> These numbers should
keep all loads below 500lb's
> force on the 2x4 strapping at each
elevation[at
> each side]. Hydaulic pressure isn't my
strong
> suite [ I'm a draftsman not an engineer]
> Hopefully
someone will look this over and tell me
> I'm an idiot.. but.. If I was
going to do it..
> this is how I'd go about it....
> Also worth
noting, if you do taper tha colum, make
> sure you secure the bottom of
it to the floor or
> it will float off.. and all your concrete
>
will come spilling out the bottom [ don't ask my
> how I know
this!]
> Actually regardless how you do it.. it would be
> worth
adding a couple concrete nails at the bottom
> to make sure it doesn't
float.. a non-tapered
> colum form could float also..
>
>
Jarrett Johnson.. [wondering how desperate Finn is
> to use/ my numbers
now...
:-) ]
>
>
>
>
>
>
>
>
---- Original Message -----
> From: "Finn Lassen"
<finn.lassen@verizon.net>
> To: "Rotary motors in
aircraft"
> <flyrotary@lancaironline.net>
> Sent: Tuesday,
June 06, 2006 9:40 PM
> Subject: [FlyRotary] OT: Concrete
forms
>
>
> > This is only remotely related to rotaries
(home
> > of my future
> > rotary-powered RV-4) so please
reply off-list.
> >
> > After having worked for three
weekends putting
> > up block and only having
> > done 1 1/2
corners out of 3 so far, I'm
> > seriously considering
building
> > forms and having the 9 16x16" columns poured
>
> rather that building them
> > up with 16x16" column
blocks.
> >
> > If anybody here on the list are familiar
with
> > making concrete forms, I
> > sure could use some
advice.
> > Columns will be 8' 8" tall and will be
> >
supporting 10' long 8x8" lintels
> > with a row of lintel blocks on
top.
> >
> > How thick does the plywood have to be to
handle
> > a 8'8" tall 16x16"
> > column of
concrete?
> >
> > I'm considering using my future 2x4 or 2x6
frame
> > wall studs to form the
> > outside corners of the
forms - two along each
> > corner of the form screwed
> >
together (8 per form).
> >
> > Another issue is the option
of tapering the
> > columns: 16x16 at bottom
> > tapering to
8x16" at top. In my mind that would
> > not change the
structual
> > strength of the columns; would save concrete
>
> (25%) and possibly require
> > less hefty plywood.
>
>
> > I sure could use some advice on both counts.
>
>
> > Keywords here are "cheaper" and "easier".
>
>
> > 16x16" column blocks are now $3.21 a piece - 13
> >
per column.
> > The extra concrete to replace one block is
about
> > $2.60 (or $1.95 if
> > tapering the
columns).
> > So I'd mainly just be paying for the
plywood
> > for the forms - seems
> > worthwhile compared to
the work of "stacking"
> > the 117 column blocks.
> >
Ideally the forms would also be able to support
> > the lintels and
lintel
> > blocks so everything could be poured in one go.
>
>
> > Finn
> >
>
>
>
--------------------------------------------------------------------------
------
>
>
>
> --
> > Homepage:
http://www.flyrotary.com/> > Archive and
UnSub:
> >
http://mail.lancaironline.net/lists/flyrotary/>
>
>
>
>
--------------------------------------------------------------------------
------
>
>
>
No virus found in this incoming message.
> Checked by AVG Free
Edition.
> Version: 7.1.394 / Virus Database: 268.8.2/356 -
>
Release Date: 6/5/2006
>
>
> --
>
Homepage:
http://www.flyrotary.com/> Archive and
UnSub:
http://mail.lancaironline.net/lists/flyrotary/>
--
Homepage:
http://www.flyrotary.com/Archive and UnSub:
http://mail.lancaironline.net/lists/flyrotary/