I am working on a project and need to know if concrete can withstand vacuum, and what thickness is needed. For easier visualization, imagine a small bowl put inside a bigger bowl, sealed on top and the space between them evacuated. The difference is this time both bowls are concrete and huge, and they must not collapse when air is evacuated. A concrete hemisphere of diameter around 1 m will be placed in an external concrete hemisphere. The vacuum should be about 15 cm thick.

What thickness should the concrete be (both the internal and external bowls), to
prevent collapse?

I will place support concrete blocks between the bowls (in the vacuum), maybe four cylindrical blocks of radius 5 to 10 cm. What do you suggest?

Note that the bowls are expected to handle temperatures up to 1500 Celsius, So please, nobody suggests reinforcing with steel.