Hi, first post. I made a pizza oven out of 6-1 -1 perlite, Portland cement and water.when it was dry in and ready to move, I noticed at the interior top of the dome, the mixture was brittle and began flaking away. As I tried to clean it up spots got bigger and deeper. It seems to be controlled now, but I have a few large divit areas to repair.
I tried to repair with the same mixture but it does not adhere well upside down. I am thinking about castable refractory cement but am wearing about if this will actually work correctly. Any advice on repair methods?