Author(s): A. Hao Meng; B. Dawei Guan
Linked Author(s):
Keywords: Solidified marine dredged clay; Seawater curing; Unconfined compressive strength; Microstructure; Cement hydration
Abstract: Soil solidification is a technique utilizing solidifying agents to enhance the load-bearing capacity, stability, and other engineering properties of weak soil. Recently, solidified soil has emerged as an innovative scour protection method for monopile foundations, offering advantages over traditional scour protection techniques. When applied underwater, the solidifying slurry boasts superior initial flowability, allowing it to form a level protective structure with the seabed, thereby reducing turbulence around the structure. Once solidified, this protective barrier demonstrates enhanced stability and durability. In the routine maintenance dredging of ports and channels, the substantial volumes of waste dredging clay generated are regarded as a challenging waste resource to manage. Its high water content, significant compressibility, and low strength make it unsuitable for direct use in engineering applications. However, solidifying this material for use as fill-in engineering projects would represent a mutually beneficial solution. To explore the application characteristics of Cement-Solidified Marine Dredging Clay (CSMDC) in marine environments, this study conducted comparative experimental research on the unconfined compressive strength of CSMDC under various admixture ratios, water contents, and curing ages in both standard and seawater curing conditions. Additionally, scanning electron microscopy was utilized to observe the microstructural changes in samples under seawater curing conditions, analyzing the mechanisms by which different variables affect the mechanical properties of the solidified soil. Experimental results indicate that the type and content of cement are crucial factors influencing the strength of solidified soil. The marine environment leads to a decrease in the strength of CSMDC due to changes in the proportion of internal cement hydration products. The initial water content of the slurry determines its early mixing degree with seawater; a lower water content during solidification enhances the slurry's resistance to seawater erosion, resulting in a denser structure and, consequently, higher ultimate strength. Polyacrylamide (PAM), when used as a thickener, not only significantly enhances the slurry's resistance to dispersion but also increases the slurry volume through molecular water absorption, thereby reducing material costs. Water reducers, although improving the mixability of the slurry, lead to reduced strength after setting, which is attributed to the significant differences in particle size distribution between the dredging silt used as raw material for solidified soil and traditional sand and gravel aggregates.
Year: 2024