Studying Characteristics and Strength of the Unsaturated Gypseous Soil with Various Saturation Degrees

The main objective of this study is to determine the appropriateness unsaturated gypseous soil as a subgrade layer for carrying foundations. A comprehensive laboratory testing program was implemented investigate geotechnical characteristics and behavior soil. Tests that are physical included specific gravity, classification tests, relative density, Proctor compactions, single double oedometer collapse potential, static triaxial compression (CU-test). Chemical testing, Scanning Electron Microscopy (SEM), Electronic Dissipation x-ray (EDS) analyses were also carried out. tests performed samples prepared at 70% density natural on natural, degrees saturation (30%, 60%, 80%) fully saturated behaviors. In both it discovered degree specimen (Moderate) with index value ranging from (4%). angle internal friction total effective stresses (f' f) decreases moisture content increases all levels. contrast, found strength cohesion (c' c) increased increasing up (60%), which led rise in shear strength. reduction ranged (38.50° 7°) respect between (34.50° stresses. Effective stress increase varied (10.0 – 26.0 kPa), (12.50 28.0 kPa). Then started gradually decreasing 80 100%, respectively. As result, (20.0 11.50 kPa) (21.50