Curing Process for refractory concrete... HELP

[Titan]

I have built an oven with a cooking area of 1m square sitting on a concrete slab (6") with 50mm sand and refractory pavers above that.
Its a half barrel shape with the walls of refractory concrete approx 140mm thick.

I have been told that I need to wait 2 months before starting the curing process by the salesman who supplied me the concrete.

I have also been told by a pro oven builder that I'm to wait 48hrs!!

Can anyone clarify how long to wait after the concrete has hardened?
And the process used as this is also conflicting and confusing?

I have been in these forums numerous times to check and fine tune my design but am unable to find the relevant information on the curing process for concrete.

I hope someone can help me as I've invested alot of money and time (3months) on this project and I'm starving

[Balthazar]

Re: Curing Process for refractory concrete... HELP

140mm!!??...that's mighty thick. My refractory layer is 75mm thick and I think I waited about a week before I applied ceramic blanket(50mm), and then the vermicrete layer(50-75mm), followed by external render(12mm).
Did you use stainless steel needles on your refractory layer?

I then slowly cured it using Heat Beads. Starting with maybe a dozen and slowly building up to about thirty or so over a period of a week.

Hope this helps.

[dmun]

Re: Curing Process for refractory concrete... HELP

I have built an oven with a cooking area of 1m square sitting on a concrete slab (6") with 50mm sand and refractory pavers above that.

Another uninsulated oven? Oh no...

I have been in these forums numerous times to check and fine tune my design

I think you missed something REALLY important, unless I'm missing something.

[Titan]

Re: Curing Process for refractory concrete... HELP

Thanks 4 the replies...
1. did'nt use any stainless steel pins or any metal watsoever...
Why use pins?? For what purpose?
2. I have insulated the oven... I think!
The refractory concrete is completely covered with a thick white blanket material (dont know what its called) and 2 layers of silver paper on top of blanket (its 'normally used to cover exterior walls in new houses) and I will more than likely cover it all in washed river sand.
The oven is enclosed by solid brick walls all around, the top will be covered by a large cement sheet after i have filled and levelled the sand.

Have I done enough??

I have found the guide to curing an oven in these forums and have already lit a few fires carefully using heat beads and wood.
The next morning the oven was still at 150 degrees.
A full 24 hrs after the fire is out the oven was at 75 degrees so I concluded that its not ALL bad!
Should I have done more in regards to insulation?
Please feel free to critisise, I've never professed to being an expert and I want to learn

[dmun]

Re: Curing Process for refractory concrete... HELP

As a barrel vault oven, you may have put your insulation under the slab, as is sometimes done. This isn't a good plan, but it was the original barrel vault design. It was problems with an oven based on this layout that caused James to design the Pompeii oven in the first place.

But if your under-floor insulation is just two inches of sand, you don't have any insulation at all. This could be a great bread oven, particularly if fired every day, but you'll find it hard to get it up to pizza temperatures.

[Titan]

Re: Curing Process for refractory concrete... HELP

but you'll find it hard to get it up to pizza temperatures.

Is it too late to rectify this?
What should i do?

[david s]

Re: Curing Process for refractory concrete... HELP

Your 2 layers of silver paper will help a little to insulate, however they will also have a tendency to stop moisture escaping. Remove them if it's not too late. Alternatively poke lots of little holes through them. You would be better off using loose vermiculite or perlite rather than sand to fill the rest.

[Titan]

Re: Curing Process for refractory concrete... HELP

I think depression has just set in.
I should have discussed my plans here before starting... oh well, nothing that alcohol wont fix!
I was under the assumption that after curing there would'nt be ANY moisture left!
I was also led to believe that the blanket was adequate insulation!

[dmun]

Re: Curing Process for refractory concrete... HELP

Is it too late to rectify this? What should i do?

Since the floor is just sitting on sand, you should be able to lift your floor refractory tiles, shop-vac out the worthless sand, and replace it with refractory insulation board. It's a pain to do, but it's better than burning forests of wood to get a barely hot oven.

[Titan]

Re: Curing Process for refractory concrete... HELP

Well, I have removed the tiles and started scraping the sand...
I wish i could pay someone to do it
Hopefully all done by the end of the weekend... sigh!

Thankyou everyone especially you dmun for your help and advice!

[dmun]

Re: Curing Process for refractory concrete... HELP

You won't regret this. The whole building process is a lot of work, you want an efficient oven at the end of the process.