The countercurrent mixer (also referred to as Eirich mixer) has a mixing pan that rotates about a vertical or inclined axis. The mixing tools are arranged eccentrically and generally rotate in the opposite direction to the mixing pan. There is a wide range of mixing tool designs. The mixing pan and tools have separate drives with independently selectable speeds. Circumferential mixing tool (whirler arm) velocities of up to 10 m/s are used for mixing concrete.
Countercurrent mixers are primarily used for concretes with fne aggregates, with microsilica or added pigments, and for concretes that must conform to stringent quality standards. These include face concrete for paving blocks, concrete for roofng tiles, SCC and UHPC. Countercurrent mixers are also often used for research purposes.
This type of mixer is more expensive because not only does the mixing tool require a rotary design and drive, but the mixing chamber does as well.