Volumetric concrete mixer
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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.
The history of volumetric mixing comes from several directions;
- The mobile mixer was patented in 1964 by Harold Zimmerman, in Ephrata, Pennsylvania, USA. Because of the patents, there was only one equipment manufacturer until the 1980s.
- Equipment manufacturers created an association, Volumetric Mixer Manufacturers Bureau (VMMB), in 1999, with six charter members including Zimmerman Ind, Inc., ProAll Reimer, Bay-Lynx, Custom-Crete, Elkin and Cementech.
Advantages & Disadvantages
- Reduces wastage and associated costs by providing exact quantities.
- No risk of premature stiffening of concrete if delays are encountered.
- Permits delivery of smaller quantities of concrete.
- Night time works do not require the re-opening of a concrete batch plant.
- Flexibility to alternate between multiple concrete mixes as required for the application.
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 systems, admix systems, fibre systems and grout concrete.
Bodies are mainly manufactured from steel, though other materials have been used to less success including aluminium.
- Casey, Jon M. "Parmer Metered Concrete offers precision and quality". Hard Hat News. Retrieved 24 November 2014.
- Volumetric Concrete
- "Sydney International Airport" (PDF). Volumetric Concrete Australia.
- SiteMix Services
- "History of the Volumetric Mixer". Volumetric Mixer Manufacturer Bureau.
- "VMMB Members". Volumetric Mixer Manufacturer Bureau.