Measurement of aggregate bond energy using ultrasonic dispersion

Abstract

Summary Numerous protocols have been developed to assess soil stability, such as wet sieving, end‐over‐end shaking and rainfall simulation, but a major limitation of these procedures is that they apply an arbitrary application of mechanical energy that is not quantified, resulting in a stability assessment that can only be related to the context in which it is being used. To address this, previous authors demonstrated that the energy ( L ) responsible for dispersing soil could be determined when using ultrasonic agitation. Changes in ultrasonic equipment, with the inclusion of a feedback system to adjust the output energy, E p , of the ultrasonic probe, preclude the assumption that E p is the same in pure water and in dispersed and undispersed soil–water systems, which may explain why previous approaches have not been routinely adopted. Our paper presents a new theory for estimating the components of the energy balance in an ultrasonic system fitted with a power‐adjusting feedback mechanism facilitating the estimate of L . Using Vertisol and Ferrasol soil samples, the components of the ultrasonic energy balance were successfully estimated and the estimate of L was greater than that reported in earlier work. When used to calculate the soil dispersion characteristic curve, it was found that the critical dispersive energy ( L d ) was in the range of 100–600 J g −1 , which appears to be much larger compared with previously published values, and the L d constituted 3–20% of the total energy applied to the soil–water system.