Crumbling firebricks on pizza oven floor

[SimonGuitar]

Hello. I am a newbie here but have often used this fantastic resource when making my own Pompeii style pizza oven.
This may well have been covered elsewhere but:
I have used firebricks (herringbone) on my pizza oven floor and have recently noticed that the bricks in the centre of the oven (where I generally position pizzas), are starting to slightly crumble.
I realise that this is probably the cause of moisture getting into the oven and me not properly curing the oven or heating it up gradually after months of hibernation.
My question is how do i fix the issue? I have some fire resistant adhesive which I have used for minor cracks on the dome. Can I use this?
To take the offending bricks out will be a nightmare as my 'tunnel' into the dome is fairly tight.

Any help very gratefully received!

[MarkJerling]

I'm pretty sure any form of "adhesive" is going to either wreck your floor or your pizzas or will likely burn off the first time you have a decent hot fire!
The only fix, really, is to remove the damaged bricks and replace them with sound floor bricks.

[SimonGuitar]

Thanks for the reply Mark. The adhesive I mean is a fire/heat -resistant formula.I feared that replacing the brick may be the only solution but getting to them will be difficult.
Will brace myself!

[JRPizza]

Simon, just out if curiosity, what kind of brick did you use on your floor? Not asking to be critical, but was wondering as I don't often hear of firebrick failing on an oven floor.

[SimonGuitar]

Hi. They were firebricks. Seemed in good shape when they were laid.

[JRPizza]

Is it bad enough to where if you sweep the floor good you see the crumbling after the next firing, or have you just noticed the bricks eroding a little? If I sweep and blow off all the ashes the bricks in the center of my oven have a "used" look and are rougher than the surrounding bricks. I can see where some of the grains have eroded away. Until I get some low spots or I can see the wear accelerating I'm not going to do anything. Do you have any pictures of what your floor looks like?

[SimonGuitar]

Thanks JRPizza. I have attached a photo. Yes they look a little rough which I get, being the centre of the oven. I just worry that they are deteriorating too much.

[JRPizza]

Yeah, that center one is kind of ugly. If it is stable though you could probably leave it for a while, but if it is constantly losing material that is going to end up in your crust it might be time for an R&R (remove and replace). Hopefully you didn't mortar them down?