Micro-structural characteristics deterioration of intact loess under acid and saline solutions and resultant macro-mechanical properties

Abstract

When exposed to chemicals, the micro-structural evolution of the loess and the impacts on the macro-mechanical properties are considered crucial for contaminated land reclamation. In this study, the micro-structural characteristics of the loess specimens that are exposed to acetic acid or sodium sulfate, are studied using scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy analyses. Further, their macro-mechanical properties are determined by direct shear tests. The corrosion of the cement between particles under acetic acid environments and the salt-induced swelling under saline conditions play an important role in the micro-structural deterioration. The cohesion and friction angle for the wetted loess are about 16 kPa and 19° respectively, while for the acetic acid-contamianted loess, they reduce to 10 kPa and 15° respectively. They, for the sodium sulfate-contaminated loess, reduce further to below 10 kPa and 13° respectively. The macro-mechanical properties show good correspondence with the micro-structural deterioration.