土の粒度分析結果に及ぼす試験条件の影響

　 Since the entire clay fraction of soils exists in the form of flocs, the type and quantity of dispersing agents used plays a decisive role in obtaining the percentage of clay-sized material in samples. To investigate the effects of testing conditions on the grain size analyses of soils, Japanesc Industrial Standard (JIS) and X-ray methods were conducted on four different types of soils with different dispersing agents and quantities.
As a result, the most suitable dispersing agents and their optimum quantity have been identified. The clay size fraction detemined a Kaolin by the JIS method is markedly affected by the formation of flocs. Consequently, analytical results obtained by the X-ray method are signlicantly more accurate than those which were obtained by JIS. It was reconimed that the main advantages of the X-ray method in engineering practice are its simphlicity, reproducibility, and speed. It also has the added advantage of tully-automated operation for grain size analysis control and data management.