Fire Brick Splits, Hearth thickness, and grout questions:

[danjmath]

About ready to lay my hearth and buy my firebricks, but had a few questions first.

First, someone was selling a load of firebricks near me for cheap. There are ~100 large and ~100 small(See picture below).
Are the smaller ones "splits"? I always assumed a split was cut in half the other way, as you would use for your pizza oven. And if I do get them, where should I use the large vs small ones?

Second, I have a 4-yard bag of perlite leftover from gardening this spring. (Ok, I'll admit I bought a little extra to hide a little pizza oven cost from my wife in the garden.)
My original plan was for a 4-inch structural concrete hearth base, with 2 layers of CaSi board below the firebrick floor. Should I instead add 2-4 inches of p-crete since I already have the perlite, then and 1 CaSi board under the floor ? I have not yet really priced CaSi yet, so I don't know if what seems like more work would be worth the savings.

Finally, I saw someone selling this grout:
http://www.ksl.com/?nid=218&ad=39648...brick&ad_cid=9
(united refractories super grout 85)
I asked, and one person told me it would not be a good replacement for home brew.
Would it be worth buying a bucket or 2 for other uses with the oven, perhaps laying the brick floor? I tried googling the product, but couldn't find any information on it.

Thanks for any help!

[RandyJ]

Thoes are not splits. I do not know what they are. A split would be 1.25x4.5x9. If the are 2.5x2x9 you could use them for the floor if there was enough to cover the area. You would just have a lot more seams. Might be just fine if they were all level with each other. One thing to worry about is if they are low duty or not. You don't want them to be to thermally conductive. Or you will burn the bottom before the top cooks. I still don't think you want the grout. Just saying.

Randy

[danjmath]

I'll have to get the sizes of those bricks to figure out what they are. I know the seller originally bought them planning to make a pizza oven, but not much else.

Thanks again on the grout, I did believe you the first time, was just wondering if it might be useful for some other part in the fire oven(not as mortar for the bricks)

[UtahBeehiver]

Dan,

Since you are from Utah, those appear to be from Geneva and are classified super duty. They will work fine but are hard to cut due to the high alumina content. Just be aware that they are hard on diamond blades. The ones you are calling splits are actually tapered arch bricks and won't work very well in the dome but will for the vent arch area. The large ones were tapered also but the other direction and can be used in the dome.