Alkali-Activated Dredged-Sediment-Based Fluidized Solidified Soil: Early-Age Engineering Performance and...

Area of Science:

• Geotechnical Engineering
• Marine Civil Engineering
• Materials Science

Background:

• Fluidized solidified soil (FSS) shows promise for marine pile scour remediation.
• Current limitations include a narrow construction window and susceptibility to erosion before curing.

Purpose of the Study:

• To systematically evaluate FSS formulations using dredged sediment, varying silica fume (SF) content (0-12%), and quicklime activation.
• To determine optimal mix designs balancing flowability and early-age mechanical properties for marine pile scour repair.

Main Methods:

• Experimental assessments included flowability, unconfined compressive strength (UCS), and direct shear tests.
• Microstructural analysis utilized X-ray diffraction (XRD) and scanning electron microscopy (SEM).
• Evaluated three water-solid ratios (WSR: 0.525, 0.55, 0.575) and four SF replacement levels (0%, 4%, 8%, 12%).

Main Results:

• Silica fume (SF) substitution extended the operational period by mitigating flowability loss.
• Optimal performance was observed at 8% SF replacement and WSR = 0.55, yielding a 22.78% increase in 3-day UCS and improved cohesion and friction angle at 7 days.
• Microstructural analysis confirmed SF's pozzolanic reaction producing C-S-H gel, but levels above 8% led to unreacted particles disrupting the matrix.

Conclusions:

• An 8% SF substitution and WSR of 0.525 represent the optimal mix for marine pile scour repair.
• Achieving a balance between flowability and early-age strength is crucial for stable FSS remediation.
• The findings provide critical insights for developing durable and effective marine infrastructure repair solutions.