Microstructural and strength variations in natural sands exposed to diverse environmental conditions

Abstract

Climatic variation affects the physicochemical properties of geomaterials and its impact on the mechanical performance of infrastructure depends on the nature and origin of the material. The long-term behavior of sand, like any other construction material, can only be fully understood by evaluating its engineering properties under extreme climatic conditions such as repeated cycles of freezing-thawing (FT), wetting-drying (WD), and heating-cooling (HC). In this study, sand samples of different origin, including beach sand and dune sand (relatively aged sands), and quarry dust (relatively young grains) were subjected to 20 independent cycles of FT, WD, and HC. Scanning electron microscopy, x-ray diffraction, and x-ray fluorescence tests were performed for microstructural, surface texture, and chemical composition of the sand samples. Moreover, direct shear test results present the engineering properties such as peak shear strength, strain at failure, and friction angle of each sand sample at the end of various cycles. It is concluded that the findings of this study may provide an improved understanding of how natural sands of different origins respond to various environmental exposure conditions.

Keywords

• Natural sands
• Climatic cycles
• Freeze-thaw
• Wet-dry
• Heat-cool
• Mineralogy