There are two main categories of concrete mixer machine: batch mixers and continuous mixers. The batch mixer produces concrete one batch at a time whereas the continuous mixer produces concrete at a constant rate.
The batch mixer needs to be emptied completely after each mixing cycle, cleaned (if possible), and reloaded with the materials for the next batch of concrete. In a continuous mixer, when fresh concrete flows out from the other end, the ingredients enter continuously from one end.
Two main types of batch mixer can be distinguished by the orientation of the axis of rotation: horizontal or inclined (drum mixers) or vertical (pan mixers). Drum mixers have a drum, with fixed blades, rotating around its axis, while the pan mixers may have either the blades or the pan rotating around the axis.
As the name indicates to the continuous mixers, materials are continuously fed into the mixer at the same rate as the concrete is discharged. They are usually non-tilting drums with screw-type blades rotating in the middle of the drum. The drum is tilted downward toward the discharge opening. The mixing time is determined by the slope of the drum (usually about 15).