#11  
Old 07-08-2007, 06:58 AM
Archena's Avatar
Il Pizzaiolo
 
Join Date: Apr 2007
Location: Alabama
Posts: 1,188
Default Re: The Picton Pizzeria

I think he wants to reclaim the wood though. Still, a dual twist in the wire ends like you used would let him do that easily enough. He could easily cut through the twist afterwards then grind the remaining wire flush. Since I doubt he's going to be reusing it for anything showy the holes shouldn't be a problem - not one wood putty wouldn't solve, anyway.

I know plastic isn't used on anything on which the bottom will show (like a bird bath). That's because any wrinkles in the plastic will be mirrored in the concrete. Depending on your design that might actually be desirable - the edges would have a bit more character and would likely look good with stucco on the oven itself. The underside would of course never be seen and as far as I know the few wrinkles there wouldn't compromise the structure - I can't actually imagine how they could.

A light coat of oil on the plastic might help with removal - but shouldn't be essential.
__________________
"He is no fool who gives what he cannot keep to gain what he cannot lose." - Jim Elliot

"Success isn't permanent and failure isn't fatal." -Mike Ditka
[/CENTER]

Last edited by Archena; 07-08-2007 at 07:01 AM.
Reply With Quote
  #12  
Old 07-08-2007, 07:53 AM
Unofornaio's Avatar
Journeyman
 
Join Date: Jun 2007
Location: Central, California
Posts: 323
Thumbs up Re: The Picton Pizzeria

"I've used builder's plastic on top of the plywood instead of oil or dish detergent. Is there any problem with that? I won't be pouring til next weekend at the earliest so I can always change it."

Plastic is not really a problem. Some notes of caution about pouring concrete in "direct contact" with plastic:
Because the plastic creates a "barrier" this rapidly accelerates the chemical heating process in the concrete, I would not suggest doing this in hot weather as you most certainly will have overheating/rapid set up issues with the slab. If you are mixing bags, on a hot day this would seriously compromise the strength of the overall slab. I think its winter there now right? so you should be OK what ever you do DO NOT COVER the TOP after the pour with plastic or anything that cant breath and keep it watered down religiously for the first 24 hrs.
Secondly where the plastic is creased or folded (on the 4 visible sides of the slab) the plastic will stick into the concrete this is not an issue as you can stucco or parge coat right over this area. Don't be tempted to pull the plastic out too soon you may not know how badly it was folded an could pull out a nice chunk of slab. After taking the forms off cut the plastic off in these areas. There is usually a bit right next to the concrete you cant get and we just use a propane torch to melt it so its not visible (if you leave this small piece and you are planning on stuccoing over it you will regret it.) The other areas that are not creased will come out very easily and there is no need for additional release agents.
Sounds like you are ready to go..Good luck
Reply With Quote
  #13  
Old 07-08-2007, 09:41 PM
ihughes's Avatar
Peasant
 
Join Date: Apr 2007
Location: Australia
Posts: 45
Default Re: The Picton Pizzeria

Thanks for the great comments.
I think I'll go around the frame again and strengthen it as Paul suggested.
I hadn't thought about the plastic and its effects on the curing.
If I cover the cement with old wet sheets will that do the trick? Temps here are generally in the 10-20Deg C at the moment although it can get a bit hotter (mid-20Deg C) on occasion.
Reply With Quote
  #14  
Old 07-08-2007, 11:36 PM
Archena's Avatar
Il Pizzaiolo
 
Join Date: Apr 2007
Location: Alabama
Posts: 1,188
Default Re: The Picton Pizzeria

I'd think sheets would be too permeable - the concrete would stick to them and the wood.
__________________
"He is no fool who gives what he cannot keep to gain what he cannot lose." - Jim Elliot

"Success isn't permanent and failure isn't fatal." -Mike Ditka
[/CENTER]
Reply With Quote
  #15  
Old 07-09-2007, 06:01 PM
Journeyman
 
Join Date: Oct 2006
Location: Adelaide, Australia
Posts: 257
Default Re: The Picton Pizzeria

Ian,

From the photo of your formwork at http://www.fornobravo.com/forum/phot...arth-floor.gif, it appears that you’re only using the plastic over the plywood base – so appearance on the sides from plastic creases shouldn’t be a problem. And no-one will see creases in the concrete under the hearth slab except the wood gatherer!

As far as covering the concrete slab after the pour, if it were me, I wouldn’t hesitate covering it as soon as it has set with a plastic membrane. I had an impervious membrane under my slab – steel flooring – and covered the freshly poured slab with plastic after 12 hours or so. I gave it a good hose down first, and during the next 7 days I ensured that it remained moist under the plastic. It actually stayed like that for 28 days as there wasn’t any action going on – at least on the hearth slab. This was late February and quite warm. The idea is to keep the concrete moist to ensure those (exothermic) chemical reactions continue so as to achieve a good strong slab.

See my post at http://www.fornobravo.com/forum/16/o...+cure#post7244 (Oven Curing) for more info on moist curing, including advice from the Cement and Concrete Association of Australia. I’ve always favoured plastic film over the concrete as it retains moisture more reliably than sheets or hessian etc. which you have to keep hosing down. You can just cover it and forget it basically. I’ve taken my cue from the many building sites which adopt this practice.

Good luck for the pour next weekend!

Cheers, Paul.
Reply With Quote
  #16  
Old 07-09-2007, 06:44 PM
Archena's Avatar
Il Pizzaiolo
 
Join Date: Apr 2007
Location: Alabama
Posts: 1,188
Default Re: The Picton Pizzeria

Quote:
Originally Posted by Hendo View Post
Ian,

From the photo of your formwork at http://www.fornobravo.com/forum/phot...arth-floor.gif, it appears that you’re only using the plastic over the plywood base – so appearance on the sides from plastic creases shouldn’t be a problem. And no-one will see creases in the concrete under the hearth slab except the wood gatherer!

...
Um, how the heck do you get the plywood base out? if it's still in there (which it will be on mine - I don't want it badly enough to try getting it out!) all you're gonna see from underneath is plywood.


Or did I miss something?
__________________
"He is no fool who gives what he cannot keep to gain what he cannot lose." - Jim Elliot

"Success isn't permanent and failure isn't fatal." -Mike Ditka
[/CENTER]
Reply With Quote
  #17  
Old 07-09-2007, 07:26 PM
Unofornaio's Avatar
Journeyman
 
Join Date: Jun 2007
Location: Central, California
Posts: 323
Exclamation Re: The Picton Pizzeria

Quote:
Originally Posted by Hendo View Post
As far as covering the concrete slab after the pour, if it were me, I wouldn’t hesitate covering it as soon as it has set with a plastic membrane. I had an impervious membrane under my slab – steel flooring – and covered the freshly poured slab with plastic after 12 hours or so. I gave it a good hose down first, and during the next 7 days I ensured that it remained moist under the plastic. It actually stayed like that for 28 days as there wasn’t any action going on – at least on the hearth slab. This was late February and quite warm. The idea is to keep the concrete moist to ensure those (exothermic) chemical reactions continue so as to achieve a good strong slab.

See my post at http://www.fornobravo.com/forum/16/o...+cure#post7244 (Oven Curing) for more info on moist curing, including advice from the Cement and Concrete Association of Australia. I’ve always favoured plastic film over the concrete as it retains moisture more reliably than sheets or hessian etc. which you have to keep hosing down. You can just cover it and forget it basically. I’ve taken my cue from the many building sites which adopt this practice.

Good luck for the pour next weekend!

Cheers, Paul.
Yes covering concrete with plastic during the cure stage or part of it is an acceptable practice but this is generally in regards to a slab on grade not when poured on another impermeable surface such as plastic.

As far as water being used to "ensure those chemical reactions continue" this is just not correct (if what you meant is different that my explanation) sometimes what we mean doesn't always come across in written words. This process happens on its own from start to finish without the addition of external water applications. The point of adding moisture via misting or putting chemical cure on the surface is to retain moisture within the slab and to retard or slow this process by retaining a high moisture content.

In the first stages of concrete cure there is a tremendous amount of heat generated and this heat needs to dissipate somewhere. The heat generated between the 2 sheets of plastic has no where to go but internal, increasing the internal temperature which accelerates the process and drastically weakens the structure.
In this application having just the center wood covered is certainly better than the whole slab sitting on a plastic sheet and then being covered by one, but as I tell our customers, my philosophy is "concrete is hard enough to put in, we do it right because taking it out is even worse" so why take the chance?

As long as were are citing sources this is where I got my info from.
Home
Reply With Quote
  #18  
Old 07-10-2007, 04:53 AM
ihughes's Avatar
Peasant
 
Join Date: Apr 2007
Location: Australia
Posts: 45
Default Re: The Picton Pizzeria

Quote:
Originally Posted by Unofornaio View Post

In the first stages of concrete cure there is a tremendous amount of heat generated and this heat needs to dissipate somewhere. The heat generated between the 2 sheets of plastic has no where to go but internal, increasing the internal temperature which accelerates the process and drastically weakens the structure.
Does this mean that putting the perlite concrete layer on top of the slab at the same time is bad as heat will be retained in the bottom concrete slab.
I saw it mentioned on another link that it is OK to do the concrete slab and insulation layer at the same time.

I only ask because I've convinced a friend to help me do the concrete work (ie I supply home brew and he does the heavt work).
Reply With Quote
  #19  
Old 07-10-2007, 07:31 AM
Unofornaio's Avatar
Journeyman
 
Join Date: Jun 2007
Location: Central, California
Posts: 323
Default Re: The Picton Pizzeria

Ihughes,
Not at all. In this case the difference would be like wrapping something in saran wrap as apposed to just putting a towel over it. Let me re-iterate, putting plastic over a slab on grade or an elevated slab as "cure" is OK the difference is when you have BOTH sides against an impermeable surface. The issue here is the concrete getting too hot.
You should be fine..
Just as a side note: If we we were to really split hairs on the subject your slab covered with plastic after it has set up and most of the initial heat has dissipated (later that evening) would probably be fine, the point is it is not an industry accepted method and has been proven to drastically reduce the psi.

Then again, about a year a go I did a slab on grade for a buddy of mines addition to their house. It was in the dead of summer here and this week we were having temps in the 100-106 range (horrible) but it was only 3 yards. I usually will NOT pour concrete after 7am winter or summer but sometimes there is nothing you can do. the only time we could get it on that day was @ 10:00am so I had them add a full dose of retardant. So the truck gets there I read the ticket to make sure everything is right check the slump shoot it out and about 3/4 of the way done the first part was so hard I could not bull float it the truck hasn't even left yet well I knew something was up because although it was 100 this shouldn't happen. To make a long story short the guy that took the order (not the batch-master) put accelerator instead of RETARDANT on the order. The concrete company sent a crew out the next week to remove the slab refund the money and reimburse my friend for my "bill". the concrete had gotten so HOT it literally turned to dust, after a week you could still scratch it with your fingernail. It was like when you mix cement, wash the wheel burro out and dump it on the ground, the silt that collects after the water evaporates very, very strange.. I believe I almost died that day trying to at least get it "flat" so we could put a topping on it if necessary, then after it didnt even set up..I was
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Stop 50 Wood Fired Pizzeria PizzaPolice Brick Oven Restaurant Reviews 4 12-05-2007 02:42 PM
Tutta Bella Pizzeria -- Seattle james Brick Oven Restaurant Reviews 3 05-29-2007 12:43 PM
Questions for (Opening a Pizzeria) southpaw Brick Oven Restaurant Reviews 0 04-15-2007 12:34 PM
Pizzeria Sorbillo -- Naples james Brick Oven Restaurant Reviews 0 01-10-2007 12:42 AM
Pizzeria in Rome james Introductions 2 04-24-2006 06:32 AM


All times are GMT -7. The time now is 03:51 PM.

Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
© 2006/10 Forno Bravo, LLC