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<p>Large quantities of dredged sediments and coal fly ash are generated annually as unavoidable by-products, posing long-term challenges for waste management and sustainable materials utilization. This study develops a lime-fly ash stabilization approach to convert high-plasticity dredged clay into a value-added geomaterial, with particular emphasis on identifying an optimal binder composition and elucidating the underlying strengthening mechanisms. A fixed lime content of 5% was combined with varying fly ash contents (0-25%), and specimens were cured for 3&#xa0;h, 7&#xa0;days, and 28&#xa0;days. Mechanical performance was evaluated using unconfined compressive strength and direct shear tests, while microstructural evolution was examined via scanning electron microscopy. Results demonstrate that both fly ash dosage and curing time significantly influence mechanical behavior. The optimal mixture (5% lime + 20% fly ash) achieved peak shear strength of 408.2&#xa0;kPa and unconfined compressive strength of 684.9&#xa0;kPa after 28&#xa0;days, representing substantial improvements over untreated and lime-only stabilized clay. Microstructural analysis confirms that strength enhancement is governed by the formation of cementitious products, primarily calcium silicate hydrate and calcium aluminate hydrate, which promote soil matrix densification and interparticle bonding. The findings establish the correlations between binder composition, reaction mechanisms, and mechanical performance, demonstrating that lime-fly ash stabilization provides an effective strategy for transforming dredged sediments and fly ash into high-performance construction materials. This approach offers both technical and environmental benefits for sustainable engineering applications, supporting circular economy objectives in waste management.</p>

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Valorization of Fly Ash and Dredged Clay into Cementitious Geomaterials: Strength Performance and Microstructural Characteristics

  • 期刊论文

  • 发表日期：

    2026年5月15日

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  • Patrick Banda,
  • Zhehao Qiu,
  • Odokonyero Charles Laber,
  • Iradukunda Patrick,
  • Jie Yin

摘要

Large quantities of dredged sediments and coal fly ash are generated annually as unavoidable by-products, posing long-term challenges for waste management and sustainable materials utilization. This study develops a lime-fly ash stabilization approach to convert high-plasticity dredged clay into a value-added geomaterial, with particular emphasis on identifying an optimal binder composition and elucidating the underlying strengthening mechanisms. A fixed lime content of 5% was combined with varying fly ash contents (0-25%), and specimens were cured for 3 h, 7 days, and 28 days. Mechanical performance was evaluated using unconfined compressive strength and direct shear tests, while microstructural evolution was examined via scanning electron microscopy. Results demonstrate that both fly ash dosage and curing time significantly influence mechanical behavior. The optimal mixture (5% lime + 20% fly ash) achieved peak shear strength of 408.2 kPa and unconfined compressive strength of 684.9 kPa after 28 days, representing substantial improvements over untreated and lime-only stabilized clay. Microstructural analysis confirms that strength enhancement is governed by the formation of cementitious products, primarily calcium silicate hydrate and calcium aluminate hydrate, which promote soil matrix densification and interparticle bonding. The findings establish the correlations between binder composition, reaction mechanisms, and mechanical performance, demonstrating that lime-fly ash stabilization provides an effective strategy for transforming dredged sediments and fly ash into high-performance construction materials. This approach offers both technical and environmental benefits for sustainable engineering applications, supporting circular economy objectives in waste management.