Engineering and Geochemical Properties of Paleosols
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The research I am conducting deals with examining the engineering
and geochemical properties of paleosols (fossilized soils) and
finding correlations between them. Engineering properties being
tested are: Slake Durability, which is a rock’s resistance to
weatherability; Atterburg Limits, which are various moisture content
at which a soil stops acting as a brittle substance and begins
acting like a plastic (Plastic Limit), and the moisture content at
which a soil stops acting as a plastic substance and begins behaving
as a liquid; the presence of microfractures via the Scanning
Electron Microscope; and Unconfined Compressability, which uses a
core sample of a rock and adds pressure until the sample fails. The
geochemical aspect that is being examined is the clay mineralogy
using X-Ray Diffractometry.
The majority of paleosols have a clay fraction and silica fraction.
The clay fraction is subdivided in to the four main groups of clay
minerals (Kaolins, Smectites, Illites, and Chlorites), which have
different crystallographic properties. Vertisols (soils comprised
mostly of smectites) are a problem for geotechnical engineers due to
the smectites ability to shrink and swell greatly (Smectites can
easily have >100% moisture vs. dry weight). We hope to be able to
link a rock’s engineering properties to composition, clay fraction,
and clay type.