I poured the insulating hearth for my Pompeii yesterday. The perlcrete does not seem to be set yet. It’s covered in plastic, and still damp. I used about an 8 to 1 mix. I ran out of perlite at the end, so the rear corners are a little shallow. That’s ok, since the oven won’t cover that part.
I’m thinking I could have blocked out all of the corners, and the landing at the front of the oven, to save on perlite, but I’d have to fill the landing with something in order to get the counter up to the level of the hearth bricks.
My real problem is that I’m concerned that the anchors for my gable house enclosure will not hold in the perlcrete. Even the parts that are starting to harden seem very crumbly. Yet, the plans for the Pompeii and the instructions for the Artigiano (and others?) indicate anchoring directly into the perlite/vermiculite layer.
If I would have read this thread I would have known to bring the forms for the perlite layer closer in, to allow for anchoring the walls.
I might be able to use the grinder or a chisel to knock off some of that perlcrete once it sets up if I can’t get the anchors to hold.