no need to beat anything to powder. The formers were mainly filled up with stone, and then some sort of liquid was poured in. That’s the only possible way it could have been done. The amount of work which would have been involved in carving all of those stones is totally prohibitive; it could not have been done.
You really don’t know anything about concrete, forms, or stone cutting, do you?
But you do have the mysterious “some sort of liquid” that somehow does everything including disappearing so that none of it exists today.
Amazing, truly amazing.