Indepth Investigation of Relationship Between Index Property and Swelling Characteristic of Expansive Soil in Bahir Dar
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Date
2007-02
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Addis Ababa University
Abstract
In this study, the relationship between Index Property and Swelling characteristic of
Expansive soil of Bahir Dar is examined.
The test results showed that the Specific Gravity ranges from 2.55 to 2.81. The Index
Property Test showed that Plasticity Index ranges from 44.5 to 76.42%. The clay content
of the soil is from 55.4 to 87%. Free Swell tests conducted on the collected samples
showed a range from 78 to 215%.
According to the Unified Soil Classification System. The soil is categorized as Fat or
Organic Clay with a potential of expansion.
AASHTO Classification System also shows that the soil is Plastic Clay with high volume
change capacity.
The dry density of the soil, which samples were taken from, ranges between 1.04 and
1.39 gm/cc. Another test conducted using one-dimensional consolidometer showed that
the Swelling Pressure of the area ranges between 75.95 and 547.52 kpa.
Relationship observed between Index Property and swelling characteristic of the area
showed that with the increment of clay content in the soil the Plasticity Index, the Cation
Exchange Capacity and the w max 24 is increased. The increment of the Plasticity Index is
in turn reflected in increasing the swelling pressure of the soil.
Dry Density of the soil also increases the swelling pressure. On the other hand Natural
Moisture content affects the swelling pressure negatively.
A single Index Property is not a reliable means of predicting the swelling pressure of the
soil while a better estimation is observed when different Index Properties are involved in
prediction the swelling pressure
The relation of (w max 24/w)*gd or (w max 24/w) with swelling pressure showed a
better indicative value than the PI for the study area.
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Keywords
Expansive; Soil