g PRWare fixed inside the drum. The revolving drum with the mixing blades gives lifting and free fall
to the mix, combes and agitates it. The mixed concrete is discharged from the open top of the
drum by tilting it downwards. The concrete tips out rapidly under gravity in an unsegregated
mass as soon as the drum is tilted. These mixers may be used to their advantage for mixes of
low workability and containing large size aggregate. The disadvantage of these mixers lies in
the fact that some mortar adheres to the drum and is left out in the drum during discharging.
To check this some amount of mortar is mixed in the mixer before the first batching called
buttering. A typical tilting mixer is shown in Plate 1.
xE 2 w
X It consists of a Non-tilting cylindrical drum with blades inside and two
circular openings at the two ends. The drum rotates about a horizontal axis (Fig. 10.4). The
ingredients are fed from one opening and the mix discharged from the other opening at the
other end by at inclined chute. The drawback is the segregation that occurs owing to slow rate
of discharge.
2h 2w
X These are also known as forced action type mixers and are used for
large size works. It consist of a horizontal non-tilting type drum (Fig 10.5). It has two sets of
blades. One set of blades mixes the mix while drum is rotated in one direction. The second set
of blades discharges the mix when the drum is reversed.
E
2 2 2w
X These are non-mobile mixers and are used either as a central
mixing plat or at precast concrete factory. Primarily these are used for making mortar but are
also used efficiently for stiff and cohesive mixes. The rollers and blades rotate in a rolling pan.
p 2IH Q h"E,2f'2w