The Oven has been on the back burner for a while but I'm back on track this season and plan to finish it up. I have decided to pour the slab out an alumina castable concrete. I'm going to insulate it from the bottom via stick pins and ceramic blanket. So 2" of the 5 inch slab became "thermal mass" instead of the vermiculite concrete. Is this too much thermal mass? I will be setting a premio 120 oven floor on top of 5 full inches of aluminate concrete.