Poured Refractory for firebox

[Machinist67]

Does anybody pour or cast their firebox with refractory cement instead of using fire brick?

[maple flats]

I used to repour outdoor wood boiler doors when in business. Never poured in a firebox. Technically you could, but you'd likely need to make a form. I don't think you could mix it stiff enough to free pour or trowel. At least not using the refractory we used, it had to be fairly loose when used. That said, there are a rather large array of refractory cements, different temperature ratings and final product strength. None are cheap. What we used was about $160/80# bag and on some doors we needed almost 3 bags. Then it had to cure for 3-4 days with a sheet of plastic covering the surface to retard drying (the rest of the door was heavy steel).
There are several grades available.
Interesting story, my brother works at a place where they do major overhauls on large planes. He had 1 plane flown in that they had placed several bags of high grade refractory as ballast (he said the planes could not fly with no weight in them for some reason, that plane flew in with little extra fuel as ballast). He got 7 or 8 bags free as well as a few other workers. Seems like he told me the plane had almost 30 bags at 40 KG each). I guess sand bags would have been just too practical!

[lpakiz]

Yes, I poured refractory cement around the upper and lower door frame. It came in a 50? pound bag, just like Quikcrete.
You will need to build forms from lumber or plywood. I should have treated the wood with drain oil or used different material for the forms, as the refractory wanted to stick to the form when I stripped them. Or maybe lined the form with plastic drop cloth sheet. Letting it dry for several days might help this problem.
I welded short bolts, nose first, to the iron to give the refractory something to hold on to. Mix just like cement, stiff as practical, then pour and TAP, TAP, TAP to get all the voids and air out. Trowel/screed and your done. Worked perfectly.

[NW Ohio]

As stated before, some oil on the forms to aid in their release. Use temporary boards to brace across the firebox and hold the forms apart/square/etc. I think you might expect it to crack, but you could use "stainless needles" to help hold everything in place even if that happens (kind of like fiber in cement).

[Scribner's Mountain Maple]

I have used pliable firebrick before. And I think that would work as a good substitute instead of Re-factory. It may be very similar chemically. I used it to rebuild my firebox on an old cook stove. Got if from a wood stove dealer locally. Came in a 50 lb box about 1'*1'*18" long. Not very big. The block of firebrick inside was partially separated in 1" chunks. It was easy to work with and mold into any shape I needed. I will be using it in my firebox when I brick my arch in a few weeks to seal around my doors and on top of the bricks to tapper to angle iron.

The advantages I think are no mixing, no troweling, it is tacky, and very pliable with a mallet or fist. Sets hard with first fire. I'm not saying use this instead of Re-factory for setting bricks, just an idea for areas that need to be formed, molded or sealed.

Ben

[PeddlerLakeSapper]

I did mine. Just kept turning it. The next day turned it again and poured another section. This was pretty easy with a 2x4 arch. You would need a pretty big shop to do a big one.

[GeneralStark]

I just poured some refractory cement a couple days ago in my intens o fire in two areas in the firebox. One was around the air tubes in the back of the arch where I built a form with some 1x material (wood) and braced it to the front of the arch. Also around the door frame where I used more 1x material to form up the edges of the bricks. CDL suggests pouring refractory around the whole inside of the door and air tubes but I will be using ceramic blanket there instead as per 802 Maple's advice.

Stuff is pretty easy to work with, but you do have to find the right consistency for filling all the voids and as others say use some wire or rod to push all the cement where you need it to avoid gaps. Because it is quite cold I used form board over the arch and to block the door and placed a small electric heater and heat lamp in the firebox to keep it warm while curing. Seems to be working well and I will be pulling the forms today or tomorrow.

[saphead]

As Ben said above "pliable firebrick" is great.Back in the day when I used to work on commercial and industrial boilers we used to call it "plastic refractory",a whole lot easier than making a form and pouring.Put it where you want it and beat it into the form/shape you want,would work great around nozzles,etc.
Craig

[Spanielslovesappin]

Pilbrico Super AB Castable Refractory is what i use all the time on incinerators and boilers... i would have used it on the arch but honestly brick was just to cheap and simple.