IMPROVED SOIL PARTICLE-SIZE ANALYSIS BY GAMMA-RAY ATTENUATION

The size distribution of particles is useful for physical characteriza tion of soil. This study was conducted to determine whether a new meth od of soil particle-size analysis by gamma-ray attenuation could be fu rther improved by changing the depth and time of measurement of the su spended particle concentration during sedimentation. In addition to th e advantage of nondestructive, undisturbed measurement by gamma-ray at tenuation, as compared with conventional pipette or hydrometer methods , the modifications here suggested and employed do substantially decre ase the total time for analysis, and will also facilitate total automa tion and generalize the method for other sedimentation studies. Experi mental results are presented for three different Brazilian soil materi als, and illustrate the nature of the fine detail provided in the cumu lative particle-size distribution as given by measurements obtained du ring the relatively short time period of 28 min.