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Dredging operations in ports, rivers, and waterways are essential for maintaining navigable depths, but they result in large volumes of dredged sediments (DS) that are often unsuitable for immediate reuse due to their high moisture content, low strength, and contamination. Stabilization and solidification (S/S) techniques are widely employed to improve the geotechnical properties of DS, making the material more stable and less prone to environmental hazards. However, ensuring the quality of stabilized DS is crucial for both environmental safety and the success of construction projects. Traditionally, quality control has relied on destructive methods, such as the 28-day unconfined compressive strength (UCS) test, which delays feedback and increases project costs and risks. Thus, the development of efficient, real-time quality control methods is necessary to optimize the stabilization process.
This thesis introduces two innovative, non-destructive methods for early-stage quality control of stabilized DS: isothermal calorimetry (IC) and electrical resistivity (ER). Both methods offer significant advantages over conventional destructive tests by providing early predictions of the strength and stability of treated sediments. Both IC and ER methods have shown to be effective in providing early, real-time feedback on the stabilization process, significantly reducing the risks associated with delayed quality control. This approach not only improves efficiency but also minimizes the financial and environmental costs associated with re-stabilization or material disposal if quality issues are identified too late.
In addition to exploring novel quality control methods, this thesis also investigates the role of the mixing procedure in influencing the mechanical properties of stabilized DS. The study reveals that mixing time is a critical factor in achieving optimal strength and homogeneity in the treated material. Specifically, the results show that sediments with higher moisture content require longer mixing times to fully incorporate the binders and develop sufficient strength. However, excessive mixing can lead to reductions in strength, indicating that there is an optimal window for mixing that varies depending on the specific characteristics of the DS, such as water content and binder composition.
The findings of this thesis highlight the importance of both real-time quality control and optimized mixing procedures in the stabilization of dredged sediments. By combining isothermal calorimetry and electrical resistivity for early predictions of strength with carefully controlled mixing procedures, this research provides a comprehensive approach to improving the effectiveness and efficiency of stabilization projects. The insights gained from this study can be applied to large-scale dredging operations, reducing the time and cost associated with quality control while minimizing environmental risks. These advancements offer a significant contribution to the field of soil stabilization, particularly in addressing the challenges posed by large volumes of dredged sediments that require treatment.