I did a test with the technic “prepacked aggregate concrete“.
First I build a little box which I divided in 25 parts with paper walls. I filled the little “rooms” as in the diagram below. When every “room” was filled with either sand or aggregate I carefully took out the paper walls and poured in the slurry. (1kg cement, 1,2 kg water). I hope the “slurry” will come down through the aggregate.
The result wasn’t so good. I think it depends on the fluidity of the slurry.