When
bagged cement is used, the field mix proportions
are usually given in terms of designated amounts of fine and coarse
aggregate
per bag of cement. The amount of
material that is mixed at a time is called a
batch.
The size of a batch is usually designated
by the number of bags of
cement it contains, such as a four-bag batch, a six-bag batch,
and so forth.
The process of weighing out or
measuring out the
ingredients for a batch of concrete is called
batching.
When
mixing
is to be
done by hand, the size of the batch depends upon the number of persons
available to turn it with hand tools. When mixing is to be done by machine, the
size of the batch depends upon the rated capacity of the mixer.
The rated
capacity of a mixer is given in terms of cubic feet of mixed concrete,
not of
dry ingredients. On large jobs, the
aggregate is weighed out in an aggregate batching
plant (usually shortened to "batch plant").Photo
above: Author:
ConcreteBatchPlants ; licensed
under the Creative
CommonsAttribution
3.0
Unported license
A
batch plant also known as batching
plant or concrete plant, a, is a
device that combines various ingredients to
form concrete. Some of these inputs
include sand, water, aggregate (rocks, gravel,
etc.), fly ash, potash, and cement.
Video explaining concept of Batching Plant
A
concrete plant can have a variety of
parts and accessories, including but not limited to:
mixers (either tilt-up or horizontal or
in some cases both), cement batchers, aggregate batchers,
conveyors,
radial stackers, aggregate bins, cement bins, heaters, chillers,
cement
silos, batch plant controls, and dust collectors (to minimize
environmental
pollution).
The
center
of concrete batching plant is
the mixer. There are three types of mixer, Tilt, pan, and twin shaft
mixer. The
twin shaft mixer can ensure even mixture of concrete and large output,
while
the tilt mixer offers a consistent mix with much less maintenance labor
and
cost.
Automation and controls
Modern
concrete batch plants (both ready
mix and central mix,) employ computer aided control to assist in fast,
accurate
measurement of input constituents or ingredients, as well as tie
together the
various parts and accessories for coordinated and safe operation. With
concrete
performance so dependent on accurate water measurement, systems will
often use
moisture probes to measure the amount of water that is part of the
aggregate
(sand and rock) material while it is being weighed, and then
automatically
compensate the mix design water target.
A look inside a Batching Plant
Types:
There
are two types of concrete Batching Plants:
Ready Mix Plants &
Central Mix Plants
A
Ready
Mix Plantcombines all
ingredients except for water at the concrete plant. This mixture
is then
discharged into a ready mix truck (also known as a concrete
transport
truck). Water is then added to the mix in the truck and mixed during
transport
to the job site.
A Central Mix Plant combines some
or all of the above ingredients (including water) at a central location.
The
final product is then transported to the job site.
Central mix plants differ
from ready mix plants in that they offer the end user a much more
consistent
product, since all the ingredient mixing is done in a central location
and is
computer-assisted to ensure uniformity of product.
A
temporary batch plant is
similar to the central batch plant but it can be constructed on a large
job
site. A concrete plant becomes central mix with the addition of a
concrete
mixer.
Mobile
batching plants are nowadays increasing becoming popular for smaller
volume and/or relatively short duration works.
urn it with hand tools. When 
