Hi Ivan - Yes segregation is a big problem when aiming at high packing factors. More reading this morning and most concrete mixes in reality are about 70% Vf maybe 75% in the lab. The theories that get to 90%Vf are based on spheres with no friction and that's the problem. Real particles are not spheres and they have sharp edges that stop them packing down. So what's your next step? Now you know the practical limits? regards Peter