Looking to do it right but cheaper .

[Bodybypizza]

Hello everyone, I am new to this group so please forgive me if this question has been asked to many times already. I am a building contractor and I am very familiar with working with concrete products and I want to build my own pizza oven at home using a gym ball. I have been researching how to make my own refractory mix and have come to the thoughts that if I use a mix of two parts white Portland cement, one part hydrated lime, one part fire clay, three parts fine silica sand, three parts perlite, and enough water to just hold it together 2” thick would work ? I am also going to use this mix for the floor of the oven and will be making a duel fuel oven with propane as one, and Wood as the other. I plan on adding another couple Of inches of this same mix to the dome also. Please help me with any advice you have as to the mix Ratios or adding other components ? I have also made my own sodium silicate (water glass) and am wondering if I should add it to the mix, if so, in what ratios or should I just brush it on the inside after casting to protect the Linings of the interior ? Thanks everyone for your support in advance ! Hope I’m not out of my mind here lol !

[UtahBeehiver]

There are 3-4 cast ovens going on right now, mostly from the UK so look under Other Oven Types. We do not recommend a couple items in your oven proposal, no perlite in the main dome, it is an insulator and weakens the dome structure, gym balls are YouTube favs but not on this site, a sand mold is preferred. You will need fire brick for the floor not home brew. Under the floor and over the dome needs insulation, budget options are 5-1 vcrete under floor, 8-10 to 1 over home brew dense cast dome. Water glass shows up once and while on the blog, how successful, don't know, the users never follow-up on success or failure.

[Petter]

Agree with UtahBeehiver and the following :

you should Not mix Sodium Silicate with Portland cement. It will make it go of too fast you be workable. It is some times used as an activator for shot-crete when coating tunnels. However, a 5:1 ratio of SS and water can be used as surface hardener / water protection on cured concrete or other portland containg items.

You could also cast your own insulating bricks using SS and Perlite. Do some mixes and aim for a density of 0.2 kg/dm3. Let dry. Cure at 150 C in a bbq or oven for 2 h. Measure weight before and after and put back in the oven until the weight does not change anymore.