Self-fall mixer has a long history, as early as the early 20th century, by the steam engine driven drum concrete mixer has begun to appear.After the 1950s, the double conical mixer of the reverse discharge type and the tilting discharge type and the split cylinder mixer came out and got development one after another.A radial mixing blade is arranged on the inner wall of the mixing cylinder of the self-falling concrete mixer.When working, the mixing cylinder rotates around its horizontal axis, and the material in the mixing cylinder is added. After being lifted to a certain height by the blade, it falls by its weight, so that the circular motion can achieve the effect of uniform mixing.The structure of self - falling concrete mixer is simple, and it mainly mixes plastic concrete.
Forced mixer has been developed and popularized rapidly since its emergence in the early 1950s.The first is the disc vertical shaft type forced concrete mixer.This type of agitator comes in two types: turboprop type and planetary type.After the 1870s, with the application of light aggregate, there appeared circular trough horizontal shaft forced mixer, which is divided into single horizontal shaft type and double horizontal shaft type, with the characteristics of self-dropping and forced two kinds of mixing.It has the advantages of small linear velocity, good wear resistance and less energy consumption, and rapid development.A mixing blade is installed on the arm of the rotating shaft in the mixing cylinder of the forced concrete mixer, and the materials in the mixing cylinder are added. Under the strong agitation of the mixing blade, the cross logistics is formed.This mixing method is much stronger than the self-falling mixing method, and is mainly suitable for mixing dry hard concrete.
Continuous concrete mixer is equipped with spiral mixing vane, each kind of material according to the mix ratio by continuous weighing into the mixer, mixed concrete from the discharge end of continuous outward discharge.This kind of mixer has short stirring time, high productivity and remarkable development.
With the development of concrete materials and construction technology, there have been many new concrete mixers, such as steam heating mixers, supercritical speed mixers, acoustic mixers, swing-plate mixers without mixing blades and secondary mixing concrete mixers, etc.
