Ultrasonic dispersion of soil in water - the effect of suspension properties on energy dissipation and soil dispersion

Abstract

The application of ultrasonic energy to soil-water suspensions for particle size analysis has been widely adopted and more recently applied to aggregate stability assessment. However, suspension properties have been reported to affect both the energy applied and the degree of aggregate breakdown. This paper investigates the effect of suspension concentration, suspension volume, gas saturation, depth of ultrasonic probe insertion and particle size distribution on the power (energy per unit time) applied by an ultrasonic probe. It also investigates the effect of suspension concentration, suspension volume, gas saturation and method of wetting the soil on the dispersion produced by ultrasonic energy applications. Where the power applied was expressed per unit soil mass, the quantity of dispersed material released by ultrasonic action was not affected by either the volume or concentration of the suspension. However, decreasing the dissolved gas concentration in suspension decreased the dispersion produced. The method of soil wetting significantly affected initial disruption but had no effect on the maximum amount of <2 and <20 µm material produced by sonification. The power applied by the ultrasonic probe was found to decrease with suspension temperature, increase with dissolved gas concentration and increase with the depth of probe insertion. Recommendations are made on the range of suspension properties that should be used for standard measurements of aggregate stability assessment using ultrasonic energy.