Sustainable self-compacting concrete: Combining industrial byproduct cements and nanosilica for enhanced properties

This study investigates the combined effect of nanosilica (NS) and commercially produced industrial byproduct-based blended cements to develop high-performance sustainable self-compacting concrete (SCC). This work employs commercially available Slag Cement (SC) with 30% ground granulated blast-furnace slag (GGBFS) and Composite Cement (CC) containing 32.5% slag, limestone, and natural pozzolan, providing practical insights for industrial implementation. An extensive experimental program, involving testing 1026 samples, was conducted to evaluate 18 SCC mixtures with NS dosages ranging from 0% to 5% by weight of total binder over curing periods up to 365 days. Fresh properties were assessed using slump flow, J-Ring, L-Box, and V-Funnel tests, while hardened properties included compressive strength and comprehensive durability indicators: rapid chloride penetration test (RCPT), electrical resistivity, water absorption, and depth of penetration under pressure. The results indicate that although NS increases viscosity, a 3% dosage provides the best overall balance between workability, compressive strength, and durability performance, as evidenced by reduced permeability, increased resistivity, and improved strength. At this optimum level, durability improved across all binder systems, reducing chloride permeability by up to 38% and water penetration depth by 41%, while increasing electrical resistivity by over 80% compared to the reference mixes. The SC-based mix with 3% NS exhibited the strongest durability performance among the investigated mixtures. Furthermore, NS effectively mitigated the low early-age strength gain typical of sustainable cements, thereby enhancing compressive strength. This study establishes a practical, experimentally validated pathway for designing high-performance, nano-engineered SCC with improved mechanical properties and durability, supporting the development of resilient and low-carbon infrastructure through the combined use of commercially available sustainable cements and nanomodification.