Fibres – preferably steel, glass or plastic fibres
– are added to concrete to improve its cracking and fracture behavior. To
achieve the expected properties, the fibres must be distributed as evenly as
possible in the concrete. This places tough demands on the mixing technology,
particularly if concrete with little water and fine grain sizes are processed
into small precast elements and used for concretes where the largest grain size
is < 6 mm. For this reason, more and more manufacturers of precast elements
made of extruded concrete are opting for mixing technology from EIRICH BIRKENMAYER
The fine-grained concrete used for small extruded components / precast elements has a stiff-plastic consistency. To ensure that the products taken from the extruder offer sufficient cohesion, plasticisers and plastic fibres are added to the concrete. This ensures the homogeneous distribution of the plasticiser and a defined separation of fibres, which are often entangled or matted, present a major challenge for concrete mixer
When processing fine-grained concretes of any
consistency, with or without added fibres, the system design of the EIRICH
INTENSIVE MIXERS offers major advantages. The mixing system (inclined rotating
pan and fast rotating mixing tool) is a further development of the ring-trough
and planetary mixer and was brought to the market 40 years ago
What sets this design apart for other mixing
processes is the fact that the rotor can run at any speeds up to 30 m/s – and
this with or against the direction of rotation of the pan. As a result, the
power input into the mix can be carefully adapted to the relevant process and
to its specific requirements.
Depending on the geometry and speed of the rotor,
very high specific mixing energy input (> 10 kW/100 kg) into the mixing
material is possible. With the mixing pan and rotor normally running in
opposite directions to each other, high-speed differences are generated, with
correspondingly high shear forces. As a result, the EIRICH INTENSIVE MIXER is
also ideal for preparing very stiff concrete mixes with added fibres. Furthermore,
addition of cement can be reduced by up to 10%.
The mixing principle with a rotating mixing pan,
rotor and material deflector ensures complete agitation and homogeneous mix of all the material
with every rotation of the mixing pan. Material transport inside the pan is
separated from mixing zone which allows a very efficient use of mixing energy. With
the EIRICH INTENSIVE MIXER, the dead zones are prevented because all the mixing
material is fed to the mixing tool blades. This also reliably rules out segregation
in the mixer.
Technical trials
regularly demonstrate improved mixing results particularly in terms of preventing
fiber segregation. For production plants, in addition to the mixers, EIRICH BIRKENMAYER
can also supply the entire plant engineering including conveyor systems, dosing
systems, weighing equipment and plant control systems. Table feeders allow
material from a batch mixing process to a continuous process.
EIRICH BIRKENMAYER can look
back on many decades of experience in many applications, including the
production of concrete roofing tiles or spacers. The EIRICH BIRKENMAYER brick
and block machines have also benefit from the EIRICH INTENSIVE MIXER design to
reduce the amount of cement used in a given mix design. All this experience will
benefit new and old customers to produce high quality concrete for every
application.
Birkenmayer South Africa is part
of the Eirich Group, a company that operates in 14 countries on 6 continents across
the globe. Birkenmayer is backed by world class manufacture within the world of
concrete mixers and brick and block plants
More information Herbert
Cullum, Tel: +27(0)11 970 3880 / Cell: +27(0)82 417 6893
e-mail: [email protected] / www.birkenmayer.co.za / www.eirich.com
