Free-falling mixers: Have a long history. As early as the beginning of the 20th century, drum-type concrete mixers driven by steam engines began to appear. After the 1950s, reverse-discharge and tilt-discharge double-cone mixers and split-drum mixers were introduced and developed one after another. There are radially arranged mixing blades on the inner wall of the mixing drum of the free-falling concrete mixer. When working, the mixing drum rotates around its horizontal axis, and the materials added to the mixing drum are lifted to a certain height by the blades and then fall by their own weight. This repetitive movement achieves a uniform mixing effect. The free-falling concrete mixer has a simple structure and is generally used to mix plastic concrete.
Forced mixer: Since its rise in the early 1950s, it has been rapidly developed and promoted. The first to appear was the disc vertical shaft forced concrete mixer. This type of mixer is divided into two types: turboprop and planetary. After the 1870s, with the application of lightweight aggregate, the circular trough horizontal shaft forced mixer appeared. It is divided into single-shaft and double-shaft types, and has the characteristics of both self-falling and forced mixing. Its mixing blades have a low linear speed, good wear resistance and low energy consumption, and have developed rapidly. The rotating shaft arm of the forced concrete mixer is equipped with mixing blades. The materials added to the mixing drum form a cross flow under the strong stirring of the mixing blades. This mixing method is much more powerful than the self-falling mixing method, and is mainly suitable for mixing dry hard concrete.
Continuous concrete mixer: Equipped with spiral mixing blades, various materials are fed into the mixer after continuous weighing according to the mix ratio, and the mixed concrete is continuously discharged from the discharge end. This mixer has a short mixing time, high productivity, and its development is eye-catching.
With the development of concrete materials and construction technology, many new types of concrete mixers have emerged, such as steam-heated mixers, supercritical speed mixers, sonic mixers, swing-disk mixers without mixing blades, and secondary mixing concrete mixers.
