The perfect sand

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The perfect sand
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Sand requires two key characteristicsGradation
Particle shape
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Gradation
An even gradation will minimise voids in a matrix
for concrete or asphalt, so minimising the amount
of paste required to hold the matrix together
(either oil of cement).
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Shape
The shape of sand particles is critical to
minimise the surface area of fine aggregate, to
minimise the amount of glue needed to bind the
ingredients and to maximise the workability of
the mixture. The flatter or more elongated the
particle the greater the surface area.
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Surface Area
As particles become smaller, their relative
surface area increases geometrically. However
the relationship between surface area and cement
requirement is not directly proportionate, indeed
Murdock showed that the minus 75 micron particles
have relatively less effect on surface area...
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Murdock
Effect of Surface Area
Murdock Surface Index
Relative Surface Area
Particle Size Fraction
Imperial
Metric
1 2 4 8 12 15 12 10 1
1 2 4 8 16 32 64 128 256
38 19 19 9.5 9.5 4.75 4.75 2.36 2.36
1.18 1.18 0.60 0.60 0.30 0.30 0.15 lt 0.15
11/2 3/4 3/4 3/8 3/8 - 4 4 - 8 8 -
16 16 - 30 30 - 50 50 - 100 lt100
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Other factors for Concrete Sand
Control over the filler content (either minus 75
micron or 63 micron particles). The effect of
crushed fine aggregates. Blending, and variable
inputs.
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Filler
These tiny particles always cause concern, due to
the possible presence of clays or other
deleterious matter that might absorb water, and
so increase cement demand. Most rock fines are
beneficial in a concrete mix, filling voids and
reducing cement demand, while improving
workability. 7- 9 of good rock filler within
the fine aggregate component of concrete has
generally proven to produce the best results.
The quality of the filler can be assessed using
a Methalene Blue test.
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Crushed Sand
The addition of crushed sand to a concrete mix
invariably adds strength, however it usually
reduces workability and can effect finishability,
depending upon how well shaped the crushed
component is, even assuming a good gradation.
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Blending and Variable inputs
Crushed sand tends to be more consistent than
natural sand. Natural sand is invariably better
shaped. Crushed sand rarely has an even
gradation, but is often blended with a fine
natural sand to achieve a good gradation. The
two critical factors in such a blend are the
shape of the crushed sand particles and the
consistency of the natural sand.
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Kemco V7 Dry Sand Plant
The Kemco V7 plant has the following unique
features A crusher capable of making lots of
500mm particles, whose output is always well
shaped and consistent. An airscreen capable of
both separating and controlling filler content,
and returning a variable controlled amount of
oversize to the crusher. An enclosed plant that
is computer controlled, both quiet and dust free
an environmental sustainable solution.
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Kemco V7 System Limitations
The Kemco V7 plant is a Dry system, and can only
process feed material with a moisture content
less than 2. The plant operates to produce a
fine finished product, it is not a significant
reduction crushing plant. Feed size should be
limited to 7mm, to make a minus 5mm sand, or to
5mm to make a minus 3mm sand. These feeds are
usually surplus or even waste products in many
quarries. While the plant takes up a relatively
small footprint, the dust collector stands over
17 metres tall.
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Kayasand V7 - 60
Kayasand is only offering the Kemco V7 60 plant
at this time. The 60 refers to plant
throughput, and on average one would expect to
see 50 tonne of Kayasand per hour, and 10 tonne
per hour of filler. Production varies according
to the amount of filler included in the feed, and
the reduction ratio required, (more recirculation
will generate more filler).
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Kayasand Kemco V7
It appears that the Kemco V7 plant is the only
plant available in the market today that is
capable of producing a single sourced
manufactured sand, that does not require
blending, and which will in some instances out
perform natural sand in concrete. It is also the
only plant that is capable of varying that
gradation to find the ideal sand for the purpose,
and able to consistently manufacture that
gradation and quality.
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Kayasand
Kemco have run over 300 tests with all types of
feed materials - in the last 7 years they have
sold nearly 50 plants in Japan. Kemco will not
sell a plant without thoroughly testing the
source rock, after which they will provide a
warranty not only for the gradation, but also for
the production and operating cost.
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Kayasand
Kayasand is the name given to sand produced by
the Kemco V7 system, so named after its inventor,
Takato Kaya. The sand features are It is well
shaped throughout the gradation Its filler
content can be precisely selected Its gradation
can be varied by recirculating oversize, and by
skimming any oversize from the discharge to the
dust collector It has a small fixed amount of
moisture added to the dicharge, which prevents it
from segregating while stored or transported,
ensuring a consistent delivered product.