Electrical Resistivity Changes in Wet and Dry Side of Optimum Moisture Content for Soils with Low to High Fines Content

Abstract

Compacted soil is an essential element in the construction of geo-structures as not any soil site on its own is ideal for the intended construction. This research is an experimental study that investigates the interactional effect of moisture and fines contents on electrical resistivity (ER) of compacted soils. The soil type used in this study is sand with 0%, 30%, and 60% fines content. A non-conductive standard proctor mold is built and modified for measuring the electrical resistivity of soil samples with different dry densities and moisture contents. The electrical resistivity measurements are conducted using four electrodes; two electrodes for injecting the current and two electrodes for measuring the electrical potential difference. The soil specimens are tested under the same electrical setup in both dry and wet sides of the soil compaction curve. The results show that there is an inverse relationship between the electrical resistivity amount and both soil density and moisture content. The plot of electrical resistivity versus moisture content indicates that even though the electrical resistivity decreases with increasing the moisture content, the rate of electrical resistivity changes is different in wet and dry sides of optimum moisture content (OMC). In the dry side of OMC, the electrical resistivity decreases with a steep slope because of an increase in both soil density and moisture content. However, on the wet side of optimum moisture content, the soil density starts to decrease and electrical resistivity moves with a milder slope just because of an increase in moisture content.