Volumetric concrete mixer

A volumetric concrete mixer (also known as volumetric mobile mixer) is a concrete mixer mounted on a truck or trailer that contains separate compartments for sand, stone, cement and water. Materials are mixed on a job site to produce the exact amount of concrete needed. Volumetric mixers mainly see use as delivery vehicles for specialty high-early strength concrete that sets too rapidly for conventional rotating-drum "agitators," and have seen use in the construction of airfield pavements. Some concrete suppliers offer general purpose concrete batched in a volumetric mixer as a practical alternative to ready-mix if quantities and scheduling are not fully known, in order to eliminate wastage and prevent premature stiffening of the mix. Additionally, typical batch plant opening fees for after-hours works do not apply.
History.
The history of volumetric mixing comes from several directions.
In 1964, Harold Zimmerman patented the mobile mixer in Ephrata, Pennsylvania. Because of the patents, there was only one equipment manufacturer until the 1980s.
Later, in 1999, equipment manufacturers created an association, Volumetric Mixer Manufacturers Bureau (VMMB). It had six charter members: Cemen Tech, Inc., Zimmerman Ind, Inc., ProAll Reimer, Bay-Lynx, Custom-Crete, and Elkin.
Modified models.
The volumetric mixer varies in capacity size up to 12 m3 and has a production rate around 60m3 an hour depending on the mix design. Many volumetric concrete mixer manufacturers have innovated the mixer in capacity and design, as well as added features including colour, admix, and fibre systems, and grout concrete.