Particle size distribution
Definition
A set of geometric characteristics that define the state of
a divided solid. Expression of the distribution of a material that has been fragmented between the
different particle size categories of which it is composed. Particle size
distribution is the measurement of the size of the granulates contained in a
batch of material and their distribution
in relation to size. Sieving is a particle size distribution method.
The behavior of water in
the ground is influenced by the type of soil present. Soils are
classified according to their particle size as follows
There are several different systems in place that denote the
particle sizes. The values given above pertain to the USDA Soil Taxonomy
system. You probably have a good idea of what gravel and sand particles
look like, but maybe not silt or clay. Silt particles are about as big as
the thickness of your hair, and clay particles are much smaller than that!
Generally, soils consist of a mixture of different particle
types, such as "sandy clay", or a "silty sand".
The Particle size
conundrum Imagine that I give you a
matchbox and a ruler and ask you to tell me the size of it. You may reply
saying that the matchbox is 20 x 10 x 5mm. You cannot correctly say "the
matchbox is 20mm" as this is only one aspect of its size. So it is not
possible for you to describe the 3-dimensional
matchbox with one unique number. Obviously the situation is more difficult for a complex shape like a grain of
sand or a pigment particle in a can of paint. If I am a Q.A. Manager, I will
want one number only to describe my particles - I will need to know if the
average size has increased or decreased since the last production run, for
example. This is the basic problem of particle size analysis - how do we
describe a 3-dimensional object with one number only?
Figure 1 shows some grains of sand. What size are they?
No comments:
Post a Comment