(IJCESEN)

Abstract

Laser diffraction method is a fast, reliable, repeatable and more precise method than the classical methods such as sieve, hydrometer and pipette. Laser diffraction method is applied to many materials such as sand, clay, abrasives, ceramics, cement, paints, foods, pharmaceuticals, cosmetics, emulsions and sprays for the determination of particle size distribution with particles in the size range of 0.02 to 2000 microns. Different sample preparation and dispersion method is required for each material because of its different inherent properties. Ultrasonic action and Calgon solution are widely used for dispersion of soil samples in laser diffraction analysis. Ultrasonic action is an application of high-frequency sonic energy to the suspension in order to disperse aggregates. Calgon is a trademark of sodium hexametaphosphate which is a chemical substance. There is no standard procedure for dispersing the soil samples in the laser diffraction analysis. The objective of this study was to develop an effective and reliable method for dispersing the soil samples. For this purpose a Malvern Master SizerX Long Bad laser diffraction instrument was used and 38 soil samples taken from various location of Turkey were analyzed. Three methods were attempted to determine the most appropriate method for dispersing the soil samples, these are; ( i ) using ultrasonic action only, ( ii ) adding 30 ml Calgon solution directly to the sample bath immediately before analysis and applying ultrasonic action during analysis, and ( iii ) soaking the soil samples in 30 ml Calgon solution for at least 12 h before analysis and then loading to the sample bath and applying ultrasonic action during analysis. Calgon solution which was used in the analysis was prepared according to standard procedure given in ASTM standard for the hydrometer method. Clay content as well as whole particle size distribution was evaluated for effectiveness of the dispersion methods. Results obtained from 38 soil samples showed that more effective method is soaking procedure in Calgon solution for 12 h before analysis.