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

Abstract

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 physicalmechanical, 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.

Microscopic Evolution of Pore Characteristics and Particle Orientation of Granite Residual Soil in One-Dimensional Compression

“…After the one-dimensional compression, the number of large pores decreased the most (by 10%); the percentages of micropores and mesopores increased by 7.1% and 2.5%, respectively, and the percentage of small pores remained nearly constant with tiny fluctuations. This variation of natural GRS pores indicates that compression of large pores contributed significantly to the deformation of the soil sample from a macroscopic perspective, which is consistent with the properties of clay according to previous studies [40]. Unlike in sedimentary clay, the pore deformation process of GRS shows a high dependency on interparticle cementation bonding, which makes it difficult for microfabrics to rearrange.…”

Comparisons of weathered lateritic, granitic and volcanic soils: Compressibility and shear strength

“…This difference is due to the fact that the formation process of LAT involves the leaching of silica from the soil, leading to relative accumulation of iron and aluminum oxides content (Alexander and Cady, 1962). The oxides of iron and aluminum would provide cementation effects, alternatively described as cladding (Airey et al, 2012;Zhang et al, 2014). Due to cementation effects, LAT would have its fine particles aggregated.…”

Effects of sesquioxide content on stress-dependent water retention behaviour of weathered soils

“…For fine grains soils such as CDV, the particles are essentially plate-like in shape, for example, see Figure 9(e), therefore, contacts may be edge-edge (EE), edge-face (EF), or faceface (FF) (Zhang et al, 2014) in the natural state. A flocculated or dispersed particles rearrangement with a preferred orientation will thus result when the soil is compacted on either dry or wet of OMC respectively (Lambe, 1958).…”