The floor the homeowner chose will look more like nature stone than concrete. It is a stamped concrete overlay that is more scratch resistant than natural stone. Dam the room with lumber strips to keep concrete in the area you want it.
Mix the concrete according to the directions with a mixing bit on a heavy-duty drill (Image 1). Mix it until it is the consistency of a thick pancake batter. Pour the fresh concrete over the floor, then go over it with a 1/4" gauge rake to bring it level (Image 2). The concrete was poured over the toilet collar flange and will be cut out later.
Once the concrete is spread, go over the area with a large rubber squeegee to smooth any peaks and to close any lines left by the gauge rake. If any wires are sticking up, you can pin them down with wire staples, and then remove when the concrete is dry.
At the end of the project, they will come back and lay down the finish coat and stamp it with the design to give it a textured look.