Abstract
In the South China Sea, calcareous sand, as a natural foundation, has the features of low mechanical properties, including its compressive strength. With the development of South China Sea islands, the problems of calcareous sand foundation are encountered in the process. However, the experience of traditional pile foundation engineering could not be applied to calcareous sand. In this study, different proportions of curing agents were added to calcareous sand to improve the compressive strength. The quantitative analysis of the relationship between the unconfined compressive strength and microstructure of solidified calcareous sand is discussed. The unconfined compressive strength was gauged from unconfined compressive strength tests. Microscopic images, acquired using a scanning electron microscope (SEM), were processed using the Image-Pro Plus (IPP) image processing software. The microscopic parameters, obtained using IPP, include the average equivalent particle size (Dp), the average equivalent aperture size (Db), and the plane pore ratio (e). This research demonstrates that the curing agent could improve the compressive strength, which has a relation with the three microstructure parameters. The curing agent, through hydration reaction, generates hydration products, i.e., calcium silicate hydrate, calcium hydroxide, and calcite crystals. They adhere to the surface of the particles or fill the space between the particles, which helps increase the compressive strength. In addition, there is a good linear relationship between the macroscopic mechanics and the microscopic parameters. Using the mathematical relation between the macroscopic and microscopic parameters, the correlation can be built for macro-microscopic research.
Highlights
In the South China Sea, calcareous sand, as a geotechnical medium formed by marine organisms, is widely distributed
Wang [2] discussed the physical properties of calcareous sand
This is because the hydration products, i.e., calcium silicate hydrate, calcium hydroxide, and calcite crystal, which are produced by the hydration reaction, adhere to the surface of the particles or fill the space between the particles
Summary
In the South China Sea, calcareous sand, as a geotechnical medium formed by marine organisms, is widely distributed. In the construction of the South China Sea project, calcareous sand, as a natural foundation, is characterized by low bearing capacity of foundation and small building load. It will meet the problem of calcareous sand foundation [1,2,3,4,5,6]. Wang [2] discussed the physical properties of calcareous sand. Wei [4] analyzed the internal pore characteristics of calcareous sand structure. Coop [5], Xiao [6], and Donohue [7] discussed the particle breakage of calcareous sand. The mechanical properties of calcareous sand are different from those of common sand
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