Agitator for twin-shaft concrete mixer - has oppositely rotating worm bands on each shaft providing two-way passage for mixed material

The agitator for twin-shaft concrete mixer comprises on both shafts (14) of the mixer two helical worm bands (23, (24) which extend in opposite helical directions and which, each starting from one of the end faces (12, 13) of the mixing trough (11), extend in diametrical opposition in the longitudinal direction of the trough, over its centre, and up to a point which is removed from the respective end face of the trough so as to form a turning chamber (40) for the material to be mixed. The shafts move towards each other, and the helical bands inter-engage freely with each other.