Concrete in Egyptian Pyramids

How is it then that a clear boundary can be seen between one stone and the one above it. I mean, if these are cast, and they are visually separate blocks, how were they poured without leaving the forms in?

They would have to be poured, set and then dragged to where they were to be placed.

Uncured concrete is heavier than limestone.

Harte

M's pyramid with part of the limestone covering





The cores stones of Khafre's

I really don't think that picture gives a conclusive proof of pouring.
There are other broken notches below. They just don't have a conpanion notch on the opposite side.