Spectroscopy and swelling soils: an integrated approach

The fact that expansive soils are a major engineering problem makes their study an
important research aspect due to the accruing cost involved in terms of economic
loss when construction is undertaken without due consideration to the probability
of their presence. Though there are several methods that have been used to
recognise their presence a need of a fast and relatively cheaper methods continues
to be a necessary undertaking. In this thesis new methods are explored where the
various aspects of swelling soil properties are investigated consisting of
engineering, geophysical, reflectance spectroscopy and remote sensing where data
from two study areas one in central Kenya and the other in southern Spain were
used.
The study relied on the establishment of indicator spectral parameters as to the
presence of three clay minerals commonly used in soil classification to swelling
potential classes namely; smectites, illites and kaolinites. This was through several
reflectance spectra analysis techniques among which are; absorption feature
mapping, derivative analysis, optical density and band normalised with centre. This
was followed by the establishment of correlations between these parameters and
the commonly used physicochemical indices of Atterberg limits, Cation Exchange
Capacity (CEC), Saturated Paste (SP), and Coefficient of Linear Extensibility
(COLE) tests. In this, their widely accepted thresholds within which soils are
assigned to a swelling potential class and provisionally to a dominant clay mineral
were used.