The Effect of Diffusion on the Sedimentation Rate of Soil Microparticles

The submitted paper presents the results of the experiment aimed at quantifying the effect of diffusion on the sedimentation rate of soil microparticles of different fractions. The goal of the experiment was to specify the determination of the texture composition of soils. The textural composition of the soil gives basic information about its hydrophysical properties. Standard methods for determination of granulometric soil composition are based on sedimentation methods. Measuring errors occur in the measurement of the soil microparticle rate, which are usually made of clay particles. Their source is the effect of diffusion. In the settling process with the gradual formation of the colloidal dispersion system, the deposition rate decreases. The rate of sedimentation of the dispersion particles approaches the rate of the mean diffusion feed in the opposite direction. Gradually, the state of dynamic sedimentation equilibrium occurs. The dispersion ratio was in dispersed system formed by clay soil particles from the Senne site. The dispersed medium was distilled water. Grain analyzes were performed by a laser diffraction method on a Mastersizer 2000 from MALVERN Instruments. The soil microparticles' rates were measured on the basis of the time and the path of particles with diameter d (90). The output of the experiment is the diffusion coefficient, diffusion average feed and sedimentation rate for soil particles of different sizes. The results of the work show that with size of sedimented soil particles, the effect of diffusion increased. On this basis, it is possible to verify the lower limit of the results of grain size analyzes based on the sedimentation method. The results of the work show that the reduction of the size of the settled soil particles increases the effect of diffusion. On this basis, it is possible to quantify the lower limit of the results of grain size analyzes based on the sedimentation method and the particle size at which dynamic sedimentation equilibrium occurs.