Relation between Shrinkage Index and Swelling Pressure for Expansive Soil found in Addis Ababa
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Date
2011-12
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Addis Ababa University
Abstract
This research is inspired by the PhD thesis work of H. B. Nagaraj from Indian Institute of
Science titled “Prediction of Engineering Properties of Fine Grained Soils from their Index
Properties”. The PhD thesis indicated that the swelling pressure has a poor correlation with the
liquid limit, a good correlation with the plasticity index and a better correlation with the
shrinkage index (liquid limit – shrinkage limit) of fine-grained soils. Nagaraj used a total set of
ten remolded soil samples representing the three extreme clay mineral types namely Kaolinite,
Illite and Montmorillonite. Also due attention was given to select pairs of soils with nearly the
same liquid limit values, but having different plasticity properties. Consequently, the research
title “Relationship between Shrinkage Index and Swelling pressure for expansive soil found in
Addis Ababa” was selected for this Master’s thesis work.
In contrast to the PhD work mentioned above, the results of this Masters study show that the
relationship between the swelling pressure and the shrinkage index for Addis Ababa expansive
clay (one type of soil) is very weak. However, a good approximation is obtained between the
normalized shrinkage index (normalized by initial moisture content) and the swelling pressure
with R2 value of 0.89. In addition to this, a better estimation is observed when multiple soil
parameters are involved in different combination in prediction of the swelling pressure rather
than only the shrinkage index. The correlations developed in this work are compared with
previously established equations such as David and Komornik (1969), Nayak and Christensen
(1974), Daniel Teklu (2004), Vijayvergiya and Ghazzaly (1973), where the first two equations
were found to be in a better agreement with the correlations developed in this work.
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Keywords
Swelling Pressure, Shrinkage, Expansive Soil