new build in Brisbane - Vibrok Caminetti

[applor]

Re: new build in Brisbane - Vibrok Caminetti

DISASTER!

Hey guys really need some help with this.

I removed the form work today. It seems the supplied concrete has just been far too thick on top and as a result none of the rebar seats filled and I have a heap of exposed re-bar.
I am hoping that it should still be strong enough but at the least I need to somehow fill in all the cracks to seal the rebar from rusting.

See the attached photos and please recommend my next course of action.

[cobblerdave]

Re: new build in Brisbane - Vibrok Caminetti

G'day
Get yourself a bag of premix cement based render, a steel float, (a rectangular trowel) and a small tin of "bondcrete.
The bondcrete painted on to ensure the new adheres to the old.
Then its a case putting some stiffish render on the floatl and using it to push the render into the surface then finishing the stroke away from yourself . Google a u tube on rendering you'll get the action
Good practice for rendering the dome.
Just for further reference concrete needs to be agitated to make it flow into spots . With a small pour like yours , just a shovel tip and agitate the concrete back on forth with that. The edges, you can get rid of the air bubbles by tapping the formwork with a block of wood
Regards dave
PS That concrete is set and looks cured to me. It will still be good and strong as well , and I'm not just saying that either.
You do have to cover that bare steel though. The alkaline cement prevents the steel from rusting.

[applor]

Re: new build in Brisbane - Vibrok Caminetti

Thanks for your reply. I'll head down to bunnings today and get what I need, ready to render it tomorrow morning.
How much render do you think I will need? Ideally I'd like to smooth over the entire area and get a smooth finish on all of it.

[cobblerdave]

Re: new build in Brisbane - Vibrok Caminetti

G'day
The render should come in 25 kg bags at the most? One of those and you'll have some left over.
You don't have to have a perfect job under there. I've never looked at the underside of that slab since I built it. Outa sight outa mind, you'll soon forget its there and no one else will see it either.
Regards Dave
PS if your worried at all Ill leave my ph no in you personal messages.

[applor]

Re: new build in Brisbane - Vibrok Caminetti

Hey Dave thanks for all your help.

I just got back from Bunnings, grabbed 2x9kg bags of cement based render.
Got a steel float, couple of buckets for mixing and a 1 litre tub of bondcrete.

On the bondcrete it says for bonding to do a light sealant coat first which needs 24 hours drying. Do you think this is necessary for my situation or can I just paint it on tomorrow and apply my render when the bondcrete is sticky?

Also picked up some animal netting (3cm) and 0.9mm wire to hold down the insulation like Liteceepers build.
That won't happen until next weekend though, since I have to get this rendering done tomorrow instead.

[cobblerdave]

Re: new build in Brisbane - Vibrok Caminetti

G'day
Bondcrete is water based. Have you got a leaf blower? Or borrow one . Recon that would dry it off real fast
Regards dave

[applor]

Re: new build in Brisbane - Vibrok Caminetti

so you're saying that I should do a sealing coat first?

Don't have a leafblower

[applor]

Re: new build in Brisbane - Vibrok Caminetti

I've just been outside brushing off the underside of the slab to do the sealing coat.

I'm finding it very dusty - I keep brushing it and more and more dust just keeps coming off. Maybe with the dry concrete mix it hasn't cured properly? Should I be hosing it to keep it damp for a few days or something?

[cobblerdave]

Re: new build in Brisbane - Vibrok Caminetti

G'day
Not having a good day are you. Don't worry about wetting anything down that concrete is cured on the surface anyway that's why it's gone the light colour. That why I suggested the bondcrete so the new would bond to old so to speak.
The bondcrete will take care of any remaining dust so that will not effect the two surfaces bonding.
So get the bondcrete on and forget about it and let it dry in outs own sweet time. It's out if the way and will not interfere with other things.
You may as well play with the oven and start that now that rendering will wait.
Trust me at our current temps your concrete is well on its way to cured. As for any lingering worries about you slab not being strong forget that to. The steel you have used and the thickness of the slab is overkill to span the area that is does.
The steel has to be covered true, but the render will sort that, and if you could ever think of a part of your oven that never gets looked at its the underside of that slab......
Regards dave

[cobblerdave]

Re: new build in Brisbane - Vibrok Caminetti

G'day
Yes I got home and had to check out the underside of my slab. Quess what I didn't use chairs I used 1/4 bricks to prop up the steel and you can see the brick bottom in the underside of the slab. Doesn't mean anything just forgot they were there.
On rendering check out a u-tube vid on rendering a pictures worth a thousand words. It's hard to render at the best of times. And on your back under a slab is not one of them. The object of the game is to seal in the steel not making it look pristine.
You push the render on with one sweep the do the next bit. No going back to play with it. Anything with Portland cement is funny stuff agitate it it goes sloppy and with render slumps and falls off. Get the render on the whole lot one sweep at a time then go back one sweep per area to smooth it off. You'll be temped to do more Dont!
Then leave it for a hour or so if you feel it with the back of your hand and its cold and wet, leave it. When it suddenly feeling dry and warm ... Great the cements going off and its time to smooth off. A dry sponge will give you a grainy surface. A steel float a slick smooth one. Choice is yours.
Hope this helps
Regards dave

[applor]

Re: new build in Brisbane - Vibrok Caminetti

Yeah I didn't have the best day got concrete dust all in my eyes/nose/throat.

I ended up hosing it down. It will be dry by morning.
I am thinking I will do the sealant bondcrete layer tomorrow and then start assembling my oven!
I can do the render next weekend.

On a side note I tried removing some of that black adhesive from the dome today. That stuff is rock hard - I was chipping it off with a broad edge chisel/hammer but it was also taking small bits of the dome off with it.
I could take to it with my angle grinder to try and get it all off though I don't know that it's really worth the trouble, do you?

[applor]

Re: new build in Brisbane - Vibrok Caminetti

Did the bondcrete sealer coat this morning.

Also laid out the insulation and the hearth pieces so I can see how it sits and where I need to cut the calsil board.

Unfortunately it seems I will definitely need to buy a second calsil board as the 1x1.2 metre just wont be big enough even with offcuts.

The dome is 90mm thick so I have allowed enough room for it to sit around the hearth and then room for one layer of insulation, with the second layer covering down to the concrete.

How did you guys cut your cailsil board? The guys at the shop recommended just using a handsaw with fine blade to minimize the dust.

Will also need to bed the hearth pieces into some sand on the calsil board as they do not sit flat. One of the pieces does not fit that well and has a decent gap in it but that will get filled with ash or whatever.

[cobblerdave]

Re: new build in Brisbane - Vibrok Caminetti

G'day
Just a suggestion get your extra insulation and get the dome into position and its insulation fitted. The render the dome and the under slab on the same day ?
Regards dave

[applor]

Re: new build in Brisbane - Vibrok Caminetti

Thanks for the advice but I think I want to get the sub render done now and do the dome separately. Especially since I want to render the dome in a different blend anyways.
Going to do it tonight, then I can pickup my extra calsil board during the week hopefully and then do the cutting on Saturday.

[applor]

Re: new build in Brisbane - Vibrok Caminetti

Did the render last night. What a nightmare - literally I think I will have nightmares of that afternoon.
The concrete render didn't like to stay on the ceiling so more than half of what I applied would fall onto the floor.
Ended up using my hands/fingers to stuff the concrete into the giant holes in the seats.
I think I should have done two different mixes. A drier mix for the seat holes that would stay in there without falling out and a wetter mix that would stay stuck to the ceiling.

Regardless I think I did manage to get all the holes covered and if I had more time I perhaps could have rendered the whole surface.

Will post a pic later - great example to everyone on what can go wrong and to avoid at all costs. Looks pretty horrible and my god the mess afterwards...