An investigation of alterations in Zhanjiang clay properties due to atmospheric oxidation

The aim of the work presented in this paper is to investigate the mechanism underlying the oxidation of the Zhanjiang clay located in the Leizhou Peninsula, China. It focuses on the changes in physical–mechanical, microstructural, mineralogical and chemical properties of the natural Zhanjiang clay after 180 days' atmospheric oxidation. The experimental results show that, owing to oxidation, the clay colour changes from greyish green to yellow. The degree of agglomeration has been improved, but the plasticity, swelling–shrinkage properties, sensitivity and yield strength have been reduced. Although the oxidation has enhanced the mechanical properties of the soil seemingly, the structural strength has been weakened, so that it would bring long-term harm to the mechanical stability of the soil. Based on the experimental findings, the mechanism underlying the oxidation is proposed; it is affected by microstructure changes and is attributed to the alterations in the connection form between particles due to the soil–solution–atmosphere reactions and kinetics, rather than the transformation of clay minerals. It is believed that the work presented in this paper would be helpful for the prediction and control of geologic and engineering hazards due to environmental changes.