Application of concentration conductivity measurement (CCM) for porosity and density profiling in granular media

Porosity and pore structure are critical parameters in geotechnical engineering which influence the stiffness and permeability of granular materials. Traditional wave-based techniques, such as bender element testing, often require complex equipment, are susceptible to noise, and rely on stiffness-to-density conversions that introduce uncertainties in porosity inference. This study introduces the Concentration Conductivity Measurement (CCM) technique as a novel, non-destructive alternative for porosity and formation factor measurement using electrical conductivity. The CCM technique was validated through calibration tests on various sands and glass beads where a strong correlation was demonstrated with empirical models and literature data. The findings exhibit CCM sensors ability to provide reliable measurements under different material typologies prepared with varying compaction efforts. The method also alleviates the shortcomings of existing techniques. Unlike wave-based methods, CCM requires simpler equipment and is not susceptible to be affected by background noise which makes the method particularly suitable for geotechnical laboratory applications. This study provides a practical and versatile framework for porosity profiling with CCM and it advances the state of the art on granular media characterization. The study also demonstrates the significant potential of the technique for applications in soil mechanics and geotechnical modelling by comparing the findings to the data in the existing literature.