Optimizing nanomaterial dosages in concrete for structural applications using experimental design techniques.

Nanomaterial-enhanced concrete offers a transformative route to improve mechanical and durability performance for structural applications. Despite the promise of nano-silica (NS), nano-alumina (NA), and graphene oxide (GO), a comparative evaluation under unified conditions remains limited. This study addresses that gap by experimentally investigating the effects of NS (1-3%), NA (1-3%), and GO (0.05-0.15%) on workability, strength, and durability properties of concrete. A two-factor statistical optimization using Response Surface Methodology (RSM) was employed to model and predict compressive, tensile, and flexural strengths as functions of nanomaterial and superplasticizer dosages. Experimental results showed that NS and GO achieved a ~ 25% increase in compressive strength, while GO yielded the highest flexural improvement (~ 40%) at only 0.10% dosage. Durability metrics such as RCPT charge passed, water absorption, and sulfate resistance were significantly enhanced across all nano-modified mixes, with NS and GO outperforming NA. RSM confirmed nanomaterial dosage as the dominant factor influencing strength, while superplasticizer had no statistically significant effect. Optimal dosages were identified for each nanomaterial to maximize performance while avoiding overdosing effects. This study provides a comprehensive, optimization-driven comparison of NS, NA, and GO in concrete, offering valuable insights for designing durable, high-performance cementitious systems using tailored nanomodification strategies.