Synergistic Design and Hydration Mechanism of seawater-resistant low-heat cement Using Industrial Byproducts
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This study presents a seawater-resistant low-heat cement (SRLHC) synthesized from industrial byproducts, where blastfurnace slag (73.3%) and fly ash (15%) were synergistically activated by a tailored silicate cement clinker-gypsum-sodiumsulfate system (1%-4%-6.7%). Through D-optimal mixture design and seawater curing experiments, regression modelscorrelating component ratios with compressive strength were established, yielding optimal 3-day and 28-day strengths of27.3 MPa and 53.5 MPa , respectively. Microstructural characterization revealed a dual-phase hydration mechanism: 1)Initial hydration: Sodium sulfate reacted with clinker-derived Ca(OH)2, generating an alkaline environment. This acceleratedvitreous phase dissolution and led to the formation of ettringite (Aft) rods and calcium silicate hydrate (C-S-H) gels, whichfilled pores without expansive stress. 2) Long-term curing : Seawater-introduced [SO4]2- reacted with residual Ca2+ to producegypsum dihydrate, while continuous slag dissolution enhanced C-S-H gel formation, further densifying the matrix. Comparedto conventional P·O 42.5 cement, SRLHC exhibited 40-47% higher strength and 105.4% seawater corrosion resistance ,attributed to the synergistic interplay of Aft and C-S-H. This work provides a sustainable strategy for marine infrastructureby valorizing industrial solid wastes while addressing durability challenges in saline environments.
Abstract
This study presents a seawater-resistant low-heat cement (SRLHC) synthesized from industrial byproducts, where blastfurnace slag (73.3%) and fly ash (15%) were synergistically activated by a tailored silicate cement clinker-gypsum-sodiumsulfate system (1%-4%-6.7%). Through D-optimal mixture design and seawater curing experiments, regression modelscorrelating component ratios with compressive strength were established, yielding optimal 3-day and 28-day strengths of27.3 MPa and 53.5 MPa , respectively. Microstructural characterization revealed a dual-phase hydration mechanism: 1)Initial hydration: Sodium sulfate reacted with clinker-derived Ca(OH)2, generating an alkaline environment. This acceleratedvitreous phase dissolution and led to the formation of ettringite (Aft) rods and calcium silicate hydrate (C-S-H) gels, whichfilled pores without expansive stress. 2) Long-term curing : Seawater-introduced [SO4]2- reacted with residual Ca2+ to producegypsum dihydrate, while continuous slag dissolution enhanced C-S-H gel formation, further densifying the matrix. Comparedto conventional P·O 42.5 cement, SRLHC exhibited 40-47% higher strength and 105.4% seawater corrosion resistance ,attributed to the synergistic interplay of Aft and C-S-H. This work provides a sustainable strategy for marine infrastructureby valorizing industrial solid wastes while addressing durability challenges in saline environments.