Vince Pitelka on thu 14 aug 08
Kelly Savino wrote:
"The place where I intend to build my caternary arch soda kiln is
currently covered with asphalt. It will have a base of cinderblocks and
two layers of hardbrick for the floor... dare I build it right on the
blacktop? Or should I pour a slab, in a form, on top of the blacktop?
Kelly -
Is the asphalt slab level? If so, I see no reason not to use it, but for
your floor on top of the concrete blocks use a layer of softbrick and the=
n
a layer of hardbrick. You can use softbrick salvaged from dead electric
kilns or whatever, but two layers of hardbrick in the floor is not
appropriate. If you use a layer of hardbrick as the hotface, and then a
layer of softbrick on top of your concrete blocks, you will never get any
appreciable heat down to the asphalt.
Those of you who are saying to cut out the asphalt and pour a slab, or
pour a slab on top of the asphalt are not thinking straight. The amount
of heat that would cause the asphalt to warp and shift would do far more
damage to a concrete slab. The solution is to insulate either one from
the heat.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Kelly Savino on thu 14 aug 08
The place where I intend to build my caternary arch soda kiln is
currently covered with asphalt.
It will have a base of cinderblocks and two layers of hardbrick for the
floor... dare I build it right on the blacktop?
Or should I pour a slab, in a form, on top of the blacktop?
Or some third option I haven't imagined yet?
Yours
Kelly in Ohio
http://www.primalpotter.com
Monica Wright on thu 14 aug 08
What is under the asphalt? Right on the ground... pour a new slab. On top of concrete... maybe. Asphalt isn't that strong if it is thin. Just look at the local walmart parking lot. Kilns are quite heavy. Have you figured out the wieght of the kiln yet? You could probably call the local paving company and see what it is rated for a certain thickness. I wouldn't pour concrete on top of the existing asphalt though for two reasons. #1 That is a lot of weight coming down on the asphalt underneath that might not be that stable anyway. #2 Most kilns on cinder blocks are at around knee height so climbing in out is perfect. Add 4 inches to that. What a pain! Just my thoughts. Good luck.
-Steve
Kelly Savino wrote:
The place where I intend to build my caternary arch soda kiln is
currently covered with asphalt.
It will have a base of cinderblocks and two layers of hardbrick for the
floor... dare I build it right on the blacktop?
Or should I pour a slab, in a form, on top of the blacktop?
Or some third option I haven't imagined yet?
Yours
Kelly in Ohio
http://www.primalpotter.com
jonathan byler on thu 14 aug 08
given that asphalt seems to soften just sitting in the hot sun, I
would do something to remove heat from the equation. It is by and
large no a very stable surface for a foundation. Best practices, as
far as I am concerned would include cutting out and removing the
blacktop under the base of the kiln, and pouring a concrete slab
bedded on compressed gravel (they sell a special kind for the
purpose) for a foundation.
jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Aug 14, 2008, at 12:18 PM, Kelly Savino wrote:
> The place where I intend to build my caternary arch soda kiln is
> currently covered with asphalt.
>
> It will have a base of cinderblocks and two layers of hardbrick for
> the
> floor... dare I build it right on the blacktop?
>
> Or should I pour a slab, in a form, on top of the blacktop?
>
> Or some third option I haven't imagined yet?
>
> Yours
> Kelly in Ohio
>
>
>
> http://www.primalpotter.com
L TURNER on fri 15 aug 08
Doug Trott wrote:
> Might be better to consider the weight of the walls distributed across the
> area of the walls (cross section), thus not including the weight or area of
> the kiln floor.
>
Doug,
You are right, sorta. If the concrete blocks are laid double thick on their
sides and crossed, then the load will be distributed over a larger area than
just the wall. However for the kiln I was using, the floor area is 9 feet
square. Distributing the load on to just the wall footprint (20-9 square
feet) will increase the load to about 9 psi.
The point is that this load is significantly lower than one might
expect. The weight estimate is probably also on the high side biased more to
hard brick than all IFB. If the existing pavement can stand up to what
appears to have been it's previous use, then the kiln should be ok.
Edouard ,
Yes, If you can dance across the floor when it's hot then so can the kiln.
If I had to cross it, and it were hot, you can be sure I would be dancing.
The layers of sand and crushed rock and sand, the cinder block, and the IFB
layer are supposed to keep the pavement cool. If the pavement melts, then it
obviously will deform. An yes, it can get that hot just from the summer
sun. There are parking lots around here you don't use after noon in the
summer, but I think Kelly lives far enough north to avoid that source of
heat.
L. Turner,
The Woodlands, TX
L TURNER on fri 15 aug 08
Kelly Savino wrote:
> "The place where I intend to build my caternary arch soda kiln is
> currently covered with asphalt. It will have a base of cinderblocks and
> two layers of hardbrick for the floor... dare I build it right on the
> blacktop? Or should I pour a slab, in a form, on top of the blacktop?
>
> Kelly, Vince
> I agree with Vince regarding insulating the bottom of the kiln thoroughly.
> It not only keeps the concret blocks cool, it keeps you fuel costs down.
>
> Several comments have been made reqarding a foundation, heaving, etc.
> Here are a couple more:
>
> What was this piece of asphalted ground previously used for and how long
> has it been there? If it's several years old, what suffering has the
> weather (rain, snow, cold, and hot) caused? If it has buckled or sunk in the
> past, it probably will again, otherwise it probably won't.
>
> Regarding the load the ground and concrecte blocks must support consider
> this. My guess of the weight of a 50 cubic kiln with 24 x 24 setting area
> and 9 inch walls, arch, and floor will weigh between 15000 and 16000 lbs.
> The footprint will be about 20 square feet. This makes the load about 5.5
> psi. A 200 pound person standing on their toes will exert a pressure of
> around 15 psi, unless they have size 12 feet. Conclusion: If you can walk
> across the asphalt on you toes without dimpling the pavement, then neither
> will your kiln.
>
L. Turner,
The Woodlands, TX
Edouard Bastarache on fri 15 aug 08
"Conclusion: If you can walk across the asphalt on you toes
without dimpling the pavement, then neither will your kiln.
L. Turner,
The Woodlands, TX"
Is this true also for asphalt softened up by heat coming form the kiln ?
Gis la revido
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
Canada
http://www.flickr.com/photos/30058682@N00/
http://pagesperso-orange.fr/smart2000/livres.htm
http://www.flickr.com/photos/potier/20321056/
http://myblogsmesblogs.blogspot.com/
Tony Ferguson on fri 15 aug 08
To add to what Vince has said,
You also do not want to pour a concrete slab on top of the asphalt either. It will eventually crack as water makes it way in between two different materials, freezes, etc.
If the asphalt is not level, you can build a wooden box (like a sand box) around the area that will sit on top and use class 5 (crushed rock mixture used for roads) or sand (if you need it to help level) or a mixture, level it, and then lay your brick foundation as Vince has stated. The class 5 will compact level. That said, if you can get away with just laying your cement block as your foundation on top of the asphalt, do it. Simpler is better.
Tony Ferguson
Vince Pitelka wrote: Kelly Savino wrote:
"The place where I intend to build my caternary arch soda kiln is
currently covered with asphalt. It will have a base of cinderblocks and
two layers of hardbrick for the floor... dare I build it right on the
blacktop? Or should I pour a slab, in a form, on top of the blacktop?
Kelly -
Is the asphalt slab level? If so, I see no reason not to use it, but for
your floor on top of the concrete blocks use a layer of softbrick and then
a layer of hardbrick. You can use softbrick salvaged from dead electric
kilns or whatever, but two layers of hardbrick in the floor is not
appropriate. If you use a layer of hardbrick as the hotface, and then a
layer of softbrick on top of your concrete blocks, you will never get any
appreciable heat down to the asphalt.
Those of you who are saying to cut out the asphalt and pour a slab, or
pour a slab on top of the asphalt are not thinking straight. The amount
of heat that would cause the asphalt to warp and shift would do far more
damage to a concrete slab. The solution is to insulate either one from
the heat.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Take Care,
Tony Ferguson
...where the sky meets the lake...
http://www.tonyferguson.net
Doug Trott on fri 15 aug 08
I think you're assuming that the weight of the kiln is evenly distributed -=
as if it were one unit. That would only be the case if the lowest layer o=
f bricks are mortared together=2C perhaps even reinforced (allowing no flex=
). Might be better to consider the weight of the walls distributed across =
the area of the walls (cross section)=2C thus not including the weight or a=
rea of the kiln floor.
Doug
> Date: Fri=2C 15 Aug 2008 12:07:25 -0500
> From: magnolia.mud.list@GMAIL.COM
> Subject: Re: kiln slab/asphalt
> To: CLAYART@LSV.CERAMICS.ORG
>=20
>=20
> Kelly Savino wrote:
> > "The place where I intend to build my caternary arch soda kiln is
> > currently covered with asphalt. It will have a base of cinderblocks an=
d
> > two layers of hardbrick for the floor... dare I build it right on the
> > blacktop? Or should I pour a slab=2C in a form=2C on top of the blackto=
p?
> >
> > Kelly=2C Vince
> > I agree with Vince regarding insulating the bottom of the kiln thorough=
ly.
> > It not only keeps the concret blocks cool=2C it keeps you fuel costs do=
wn.
> >
>=20
>=20
> > Several comments have been made reqarding a foundation=2C heaving=2C et=
c.
> > Here are a couple more:
> >
> > What was this piece of asphalted ground previously used for and how lo=
ng
> > has it been there? If it's several years old=2C what suffering has the
> > weather (rain=2C snow=2C cold=2C and hot) caused? If it has buckled or =
sunk in the
> > past=2C it probably will again=2C otherwise it probably won't.
> >
> > Regarding the load the ground and concrecte blocks must support consid=
er
> > this. My guess of the weight of a 50 cubic kiln with 24 x 24 setting a=
rea
> > and 9 inch walls=2C arch=2C and floor will weigh between 15000 and 1600=
0 lbs.
> > The footprint will be about 20 square feet. This makes the load about =
5.5
> > psi. A 200 pound person standing on their toes will exert a pressure o=
f
> > around 15 psi=2C unless they have size 12 feet. Conclusion: If you ca=
n walk
> > across the asphalt on you toes without dimpling the pavement=2C then ne=
ither
> > will your kiln.
> >
>=20
>=20
> L. Turner=2C
> The Woodlands=2C TX
Jennifer Boyer on sun 17 aug 08
Well, here are the gorey details of my first kiln. Use my experience
as you wish:
In 1975 I built a sprung arch softbrick downdraft 36 cu ft propane
kiln in Cabot Vermont using the plans that Harry Dedell used to sell
out of Cutter Ceramics in CT. He called for the standard amount of
cinder block and hardbrick for the floor, but it needed to be on a
concrete slab according to his directions. I asked around and a few
people said folks had been having good luck with FLOATING slabs: That
is pouring a 6 inch slab on top of the ground with no footings. I did
that, using a piece of ground near my studio that had been leveled
with a bulldozer.
About 2 years later something weird was happening with my burners,
which were plumbed using pipe that was attached to the frame of the
post and beam building protecting my kiln from our VT winters. The
burners on one side were seeming to get closer to the kiln and the
ones on the other side were getting farther away! I switched to
flexible piping so I would move the burners, but the situation got
worse every year.
Finally I realized my whole kiln on the slab was tilting!! The ground
was settling on one side and the slab was tilting. SO I had to dig
holes under all 4 corners of the slab itself, jack the slab up on the
low side and build 4 foot footings under the corners using
cinderblocks. NOT FUN.
This was at a time when we couldn't afford to pay people to do this
stuff, so Tony and I did it ourselves.
SO beware of the ground condition. You live in an area with winter.
The ground will be freezing and thawing and heaving under this new
weight. I wouldn't worry so much about the asphalt softening in the
heat: I have a car kiln and I have all sorts of combustibles that blow
in under the car but never even get singed: leaves, packing peanuts.
BUT that piece of ground under the asphalt hasn't been prepared to
carry weight. The asphalt has no strength or integrity on it's own. I
doubt you could find anyone that would suggest building a kiln on bare
ground and that is what you would be doing essentially. THe only
difference is that possibly if the ground you are talking about has
been a driveway it may have been compacted alot already by traffic.
But if I were you I'd pour a slab.
Jennifer
On Aug 14, 2008, at 1:18 PM, Kelly Savino wrote:
> The place where I intend to build my caternary arch soda kiln is
> currently covered with asphalt.
>
> It will have a base of cinderblocks and two layers of hardbrick for
> the
> floor... dare I build it right on the blacktop?
>
> Or should I pour a slab, in a form, on top of the blacktop?
>
> Or some third option I haven't imagined yet?
>
> Yours
> Kelly in Ohio
>
>
>
> http://www.primalpotter.com
***************************
Jennifer Boyer
Thistle Hill Pottery
Montpelier, VT
http://thistlehillpottery.com
http://jboyerdesign.com
http://artisanshand.com
***************************
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