| Mineral Composition
The mineral composition is
determined by the type and arrangement of the atoms
which make up the crystal structure of the solid
matter. In the more common clay minerals certain
atomic combinations are found to be repetitive. One such
combination is a plate like arrangement of silica
tetrahedra, each of the latter consisting of four
tightly packed oxygen atoms and a central silicon
atom. Another basic combination is a sheet
comprised of aluminium octrahedra, each of the latter
consisting of six oxygen or hydroxyl ions arranged
around an aluminium atom. The hexagonal planar
network of silica tetrahedra is known as a silica
sheet. The network of octahedral units is termed a
gibbsite sheet. The crystal structure of many clay
particles consists chiefly of alternations of these
sheets. See diagram below.
Fig: 1 Platelet
Orientation The above
diagram shows the different alternations of the silica
and gibbsite sheet. These three different clay
types have different engineering characteristics as a
result of their differing platelet formations. The
montmorillonite makes greater use and has a greater
affinity for water than the kaolinite.
Consequently, it is regarded as a more expansive clay
and less suitable for use as an engineering
material. However, all of these clays have the
common property of plasticity, that is they all readily
react with water and are bound together by Van der Waals
forces. As water moves in and out of the soil
system these platelets are continually reacting with the
water in hydration and dehydration cycles. Again,
this has a major consequence on the engineering
performance. This fundamental property allows for
manipulation of the chemistry of the clays and therefore
it can be engineered, and the overall performance of the
soils, by allowing the substitution of ions into the
structure in place of the water molecules. By
blanketing the points of contact on the clays molecules
that are frequently taken up with water molecules with
more stable ions the engineering performance can be
greatly enhanced, thus reducing the desire of the clays
for the dissociated H2O molecule. It is this
fundamental property that Endurazyme acts on by
providing selected ions that help control the hydration
cycle of the materials and, consequently, its
engineering performance.
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