Electrical Properties Of Clay In Relation To Moisture Loss

Subsidence of buildings situated on clay soils can be a serious insurance problem in dry summers. In order to investigate subsidence and monitor its progress, non-invasive techniques that provide information on soil properties have enormous potential. To help assess the application of new electrical tomographic monitoring techniques, the electrical properties of seven geographically extensive clays and their relationships with moisture content have been determined. It is found that resistivity increases slowly as moisture content decreases to between 10-15% of the total saturation, beyond which resistivity increases rapidly. As electrical resistivity of clay is also dependent on ambient temperature, this must be monitored and corrected for. The results suggest that electrical resistivity could be a useful indicator of moisture content in clay soils.