Crack in vermiculite hearth floor

[Gagowhani]

Hello
I was replacing a damaged brick on my oven floor and noticed my vermiculite/cement base is badly cracked. I built this oven 5 years and I have no cracks in the dome what so ever.
I want to know what’s the best solution to repair these cracks before I place the bricks back in place.
thank you
HG

[UtahBeehiver]

Give us a few more details, how thick is the vcrete? what ratio did you use? Is there a structural concrete hearth under the vcrete?

You are one of the few builders I have seen that has had to replace bricks in the floor. were they spalling or cracking?

[Gagowhani]

Thank you for your quick response.
its 4 inch thick. I used the recipe recommended by FB. Yes there’s is a 4inch concrete under the VCrete. I am planning on flipping the bricks on the floor to make them look cleaner and also had few that are chipped.

[Gagowhani]

I would like to know what material you recommend to fill these cracks

[UtahBeehiver]

Do you think you need to fill them? It is an insulating layer not really a structural layer. If you feel like you really need to fill them then a home brew 3,1,1,1 sand, lime, portland, clay or a fireplace ready to use mortar.

[Gagowhani]

Got it. Thank you for the advice.
do you know where I can get fireclay to place back the oven floor bricks back?
What material do you recommend I use for brick oven floor?