Abstract:
A considerable Welkite town surface area is covered by expansive soils which have a tendency to
undergo volume change due to change in water content with seasonal moisture variation. Civil
engineering structure built on such soils show damage due to uneven movement caused by swelling and
shrinking of the soil.
The focus of this study is to develop relationship between index properties and swelling pressure of the
expansive soils found in Welkite town. Conducting swelling pressure test is time taking and expensive
when compared with a simple index property tests. Therefore, it is helpful and has engineering
applications to develop correlation formulas for estimating the swelling potential from simple index
properties tests.
The new formulas has been developed, by taking one or more of the soil property parameters (Liquid
limit, plastic limit, moisture content, dry density and plasticity index) in different combinations. To
develop the equations, 16 test results have been used as an input data for SPSS 21 windows software.
The equations are then tested for two control samples. The best equation was proposed, and conclusions
and recommendations were made. Lastly, future works were suggested.
The test results showed that the Specific Gravity ranges from 2.68 to 2.82. The index property test
showed that plasticity index ranges from 46 to 65.1%, liquid limit ranges from 87 to 109%, plastic limit
ranges from 37 to 48%, and liquidity index range from -0.15 to 0.18. The clay content of the soil is from
65.89 to 74.62%. Free swell tests conducted on the collected samples showed a range from 160 to 221%.
The undisturbed sample test results showed that the swelling pressure of the area ranges between 74 and
390 kPa, ϒd ranges between 1.19 and 1.48 and moisture content range from 34 to 48%.
The new formulas were developed, by taking one or more of the five parameters (liquid limit, moisture
content, plastic limit, dry density and plastic index) in different combinations. The equations are
developed by using SPSS 21 for windows software. Among the equations, equation 4 fulfills the entire
requirements.
