What are the main components of 3D printing mixtures?

The cement mixture suitable for 3D printing consists of the following main components: cement (CEM 32.5 / 42.5 R), silica river sand (maximum grain size 1 mm), water, viscosity modifying and super plasticizing admixtures (to promote pumpability and maintaining the consistency suitable for extrusion). The quantities of each single constituent depend on multiple factors such as: the expected performance, the containment of shrinkage, the programmed workability and setting time for printing, the specific weight. Consider a water/cement ratio = 0.3 and cement/sand ratio = 0.5.