Advanced Performance Evaluation of Self-Compacting Concrete Incorporating Marine Sand and Ternary Cementitious Binder Systems.

The investigation evaluated six M40-grade SCC mixtures containing manufactured sand or river sand with 0%, 10% and 50% sea-sand replacement under a constant ternary binder system. The principal conclusions are: • The ternary binder containing 65% OPC, 30% fly ash and 5% GGBS was successfully applied across the six mixtures with a total cementitious content of 590 kg/m³. • Slump-flow spread decreased with sea-sand replacement. The manufactured-sand series decreased from 740 mm to 710 mm and 700 mm, while the river-sand series decreased from 690 mm to 685 mm and 680 mm. • All six mixtures exceeded the 48 MPa target mean strength at 28 days, with compressive strengths of 50.5–64.0 MPa. At 90 days, TMSR50 reached 67.0 MPa and TMSM50 reached 64.8 MPa. • Split tensile strength increased with curing age, with 90-day values between 3.28 and 3.65 MPa. No systematic adverse effect of sea-sand replacement was observed across the six mixtures. • Flexural strength increased from 5.0–7.8 MPa at 28 days to 9.0–10.6 MPa at 90 days. TMSM50 and TMSR50 exhibited particularly strong later-age flexural performance. • Partial sea-sand replacement is technically feasible within the investigated SCC system, provided that aggregate grading and fresh-state flow are appropriately controlled. TMSM50 and TMSR50 merit further structural validation, but a universal optimum replacement level cannot be established without durability, cost and reinforced-member data.

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