Mechanism and Crack Research of Sodium Silicate-Slag-Basalt Fiber Ternary Synergistic Solidification of Silty Clay

Why It Matters

The breakthrough offers a low‑carbon, high‑performance alternative to conventional cement‑based stabilizers, reducing shrinkage and cracking in critical infrastructure projects across the Yellow River Delta and similar regions.

Key Takeaways

• Optimal mix: 7.76% sodium silicate, 9.96% slag, 0.30% basalt fiber.
• 7‑day UCS reaches ~157 kPa, 214% improvement over untreated silt.
• Basalt fiber creates 3‑D network, bridges microcracks.
• Sodium silicate activates slag, forming C‑S‑H gel and ettringite.
• Failure mode shifts from brittle shear to ductile deformation.

Pulse Analysis

Silty clay soils, common in river deltas and reclaimed land, suffer from low shear strength, excessive shrink‑swell behavior, and a propensity to crack under load. Traditional stabilization relies on Portland cement, which delivers strength but contributes significantly to CO₂ emissions and can exacerbate brittleness. As infrastructure projects increasingly prioritize sustainability, engineers are turning to waste‑derived binders and natural fibers that can provide comparable performance with a smaller environmental footprint. The search for such green alternatives has intensified in China’s Yellow River Delta, where rapid development pressures demand resilient, low‑impact ground improvement solutions.

In the recent study, a ternary composite of sodium silicate, ground‑derived blast‑furnace slag and basalt fiber was optimized through a central composite rotational design. The model pinpointed an optimal dosage of 7.76 % sodium silicate, 9.96 % slag and 0.30 % basalt fiber, delivering a 7‑day unconfined compressive strength of roughly 157 kPa—more than double the strength of untreated silt. Alkali activation of slag generated calcium‑silicate‑hydrate gel and ettringite, which filled pores and lowered crack ratios, while the dispersed basalt fibers formed a three‑dimensional lattice that bridged emerging microcracks. Digital image correlation and particle image velocimetry confirmed a transition from brittle shear localization to ductile expansion, indicating superior energy dissipation.

The demonstrated performance positions the sodium‑silicate‑slag‑basalt fiber blend as a viable, low‑carbon alternative for large‑scale ground improvement, especially in regions where industrial by‑products are readily available. By reducing reliance on Portland cement, project developers can lower both material costs and carbon footprints while achieving enhanced durability against cracking and settlement. Future work may explore scaling the mix for field applications, integrating additional waste streams, and evaluating long‑term durability under cyclic loading, paving the way for broader adoption of eco‑friendly geotechnical materials across infrastructure sectors.