Comparison of the dispersibility of Çukurambar and Ostim clays using double hydrometer, double lazer diffraction and pin hole tests

Dispersive clays are highly erodible minerals when their pore water includes high amaunt of Na ions. This clay can dispers even in distilled water and they form a suspension. Use of dispersive clays give rise to important problems especially for hydroulic stroctures, earthfill dams and road fill projects.In this study, dispersibility of clays were compored using various test for this purpose; Ankara clay samples were taken from trial pits excavated in Ostim and Cukurambar districts of Ankara city. Index tests and double hydrometer and double lazer diffraction tests were carried on taken samples. Disturbed samples of Ankara clay were compacted using standard proctor with varying water contents and varying sodium hexameta phosphate ( ? Na PO ? _3) concentration. On these compacted samples, pin hole tests were performed, and the relatron ship between these tests were examined using graphs.As a result of this study, it was determined that both double hydrometer and double lazer diffraction tests are repeatabe, ( ? Na PO ? _3) concentration incrases dispersivitiy,and both Cukurambar and Ostim clay samples are non dispersible (ND4, ND3) under normal conditions.