Measurement of continuous air content and air conductivity for sand using sound resonance

Abstract

At present, acoustic method for evaluation of the continuity between the atmosphere and soil air hasnot been fully investigated. We evaluated impedance at a sample surface using sound resonance, and estimated the amount of sample air affected by the resonance and the conductivity of the sample. Sand and glass beads were used for a comparison of the air conductivity estimated using the acoustic method and the conventional method based on Darcy’s law for air flow. Our results show that the impedance measurement provided good estimations of the continuous air content. We can more precisely determine the proportion of continuous air in the sample by combin-ing the acoustic method with typical bulk and particle den-sity measurements. Our calculation procedure was valid until the amount of air in the sample was less than 20 cm3. Comparison with results of the conductivity tests show that the impedance measurement provided the air conductivity for sample air connected to the atmosphere through one side of the sample.