Another UK oven project

[Les]

Re: Another UK oven project

When I poured my hearth, I brought in a yard of ready mix (5 sack). That required enough shoveling as it was.

Les...

[karl]

Re: Another UK oven project

Matt,

Maybe some help here:
Mixing Concrete, concrete, sand, cement, ballast, Calculator

regards from karl

[dmun]

Re: Another UK oven project

You may want to look at my concrete mixer thread, as well.

http://www.fornobravo.com/forum/f6/c...asics-790.html

[nissanneill]

Re: Another UK oven project

To improve your concrete surface, after you have screeded it and lightly trowelled ot with a long wooden trowel, mix a toppong of 1 part concrete sand (like a washed coarse river sand) with 1 part portland. When your concrete has initially set enough to walk on carefully (2-3 hours after laying), sling handfulls of the topping over the slab and work it up with a wooden trowel. It will draw water out of the cement and go to a thick slurry which can be finished with either a woodern trowel ( a non slip slightly rougher texture) or a flat steel trowel for a smooth finish. You can also use a household or garden brush to produce a non slip surface for paths/driveways. You can also add some colouring in the form of an oxide if you wish to have a coloured finish rather thanuse a lot more to colour the entire concret thickness.

Neill

[aureole]

Re: Another UK oven project

More work done this weekend: I've finished the evil backbreaking parts - another tonne and a half of concrete poured this weekend and the block stand is finished, covered and curing. I borrowed the idea seen elsewhere on a UK build of putting a sleeper in as a lintle on the front: my plan is to render in terracotta mortar, and do a reveal on the lintel.

Minor niggles- I think I've made the block stand slightly too large - it's 1980mm square - I think using 9" blocks rather than 8" ones enlarged everything too much (I figured too big is always better than too small though). Also, I got a nice finish on the concrete, but then covered it too soon, so the plastic has fouled the surface a little.

I also went through 3 tons of ballast, 20 bags of cement and two cement mixers - the first one I borrowed died halfway into forming the hearth slab. Luckily for me, my neighbour has one I was able to beg/borrow/steal to finish off the work. He also gave me six bags of cement to finish the job. Nice guy!


I'm really glad I've got the stand finished, working in 29c (85f+) sunshine pretty much killed me. At least it's mostly fiddly stuff now.

[aureole]

Re: Another UK oven project

I'm now deciding between a low and high dome. I was leaning towards the Naples design, but I'm nervous about setting a really aggressive angle and having to buttress the full brick soldier course - I've ordered (total) 300lbs of refractory concrete (actually very fine aggregate so basically mortar) and some air-drying mortar for fine/close work.

[aureole]

Re: Another UK oven project

Finally got to put my celaboard down, and start laying the base bricks.

I only had a 7" tile saw to work with, so I've been scoring and breaking the bricks: done 110 bricks in preparation, hopefully will speed up the rest. The tile saw has made a bit of a mess of me too (see photos!). The codename of this project will be forno rustico I think - I don't think my workmanship is up to much, sadly - but if it stays up, I'll be happy.

After faffing with several different premix products - an airdrying superplastic turned out to be useless (except I used it for the oven floor brick setting) and a refractory concrete that has zero adhesion. Luckily, my back-up plan of buying fireclay "just in case" has worked, so I'm on the forno homebrew mix - seems to be okay so far, but I'll go look tomorrow to see how the first course has held.

[Frances]

Re: Another UK oven project

The codename of this project will be forno rustico I think

It looks fine to me!

Don't worry, we need the build of rustic ovens to be documented in order to counteract things like Les' build... else no one except the professionals will even attempt it. And that would be a great shame.

I'm sure you'll end up with a fantastic oven, which bakes great pizzas.

[aureole]

Re: Another UK oven project

As long as it stays up, I'll be happy - there's a few bits that aren't lovely, but also, that no-one will ever see.

I'm on course 4 now - photos later today, and I'm having a great time. The homebrew refractory concrete is a little tough to mix, but once that's done, it's quite a pleasant experience to potter around the oven and get everything nicely set.

[egalecki]

Re: Another UK oven project

My oven isn't much to look at on the outside under all that blanket and stuff, but it's amazing how much you don't see when it's finished! Keep it clean inside and everyone will think you're a genius brickie. And watch that you don't get a lot of brick edges lining up over each other- stagger them as much as possible, although as you get up near the top it's really hard to do.

Don't cut TOO many bricks ahead- at some point near the top you'll want to switch to using 1/3 bricks. The halves get too big when the hole gets small- you don't want to do too much recutting.

[aureole]

Re: Another UK oven project

Yeah, I think I overdosed on the 1/2 bricks- I may have to recut and do 1/4 bricks (or alternate 1/2 and 1/4 bricks) - what course do you think about switching over? As far as I can tell, I'm going to have 1 soldier course then 9 other courses. Probably.

[Breven]

Re: Another UK oven project

You'll also need some full bricks for your arch. 8-10 generally. With different dome height and radius, will come different cuts on each brick. I don't think there is a specific course when you should start cutting a thinner brick, the bricks should tell you. (if they haven't started talking to you yet, I recommend another beer or two).

[adman2u]

Re: Another UK oven project

You can make project stonger by adding fiber in the cement. I looks exactly like nylon rope cut in one inch pieces and then pulled apart this mixes in and adds great strength against cracking. I got mine at our concrete plant a bag was $17 and that is more than enough for five ovens. I used it in all the places I poured solid except were extreme heat was an issue. In those places i used vermiculite in the cement 60/40v. I have read you can use sawdust for the same thing - the wood burns out and leaves cavities for insulation. For me it was easier to go to garden center for vericulite. I put two pieces of cardboard between vermiculite cement and regular cement as an expansion joint.

[aureole]

Re: Another UK oven project

Finished up to the fourth course today. Right about there, the angle is now sufficient to make it ... interesting ... getting the bricks to stay put. It's a nice feeling locking in a course though.

Major problem/worry of the day: my entrance/vent area is a mess. The fibreboard under the base bricks got wet and the sides compressed it: at an angle! I figured the mortar tying the entrance bricks to the dome would probably crack, I didn't expect that before it even cured! (I couldn't easily tie the vent bricks to the dome course as I wanted the reveal and couldn't do a nice cutting job on them). I'm hoping that tomorrow it'll be okay enough to go on - my plan is to put a bracket in to buttress it, or I'll add a load of refractory mortar to buttress it. Providing it's still standing tomorrow.

Otherwise, I'm pretty happy I've got to where I am. The gazebo should now hopefully mean I'm prepared for a bit more weather that previously.

[aureole]

Re: Another UK oven project

Does everyone else worry like mad about every little bit of the project? I'm going crazy fretting about the rain, the wet fibreboard, the entrance cracks, the dome collapsing, etc.