University of Tehran Civil Engineering Infrastructures Journal 2322-2093 Articles in Press 2026 05 20 Experimental and Numerical Optimization of the Mechanical Properties of Basalt Fiber-Reinforced Self-Compacting Concrete Using the Box-Behnken Response Surface Methodology 107063 10.22059/ceij.2026.393112.2289 EN Amir Hossein Derakhshan Nezhad Ph.D. Candidate, Department of Civil Engineering, Faculty of Civil Engineering, Semnan University, Iran 0009-0008-0994-8590 Seayf Allah Hemati Assistant Professor, Department of Civil Engineering, Faculty of Civil Engineering, Semnan University, Iran 0000-0001-5732-1153 Omid Rezaifar Professor, Department of Civil Engineering, Faculty of Civil Engineering, Semnan University, Iran 0000-0002-4753-7775 Journal Article 2025 04 08 This study investigates the mechanical behavior and fresh properties of basalt fiber-reinforced Self-Compacting Concrete (SCC) using Response Surface Methodology (RSM) with a Box-Behnken design at three levels to optimize variable interactions. Twelve SCC mixtures were prepared, varying basalt fiber contents (0, 0.5, 1.25, 2 vol.%) and nanosilica dosages (6, 8, 10 kg/m³). Fresh properties were evaluated via Slump Flow, V-funnel, L-box, U-box, and J-ring tests, yielding slump flows of 650–800 mm and confirming workability. Hardened properties compressive strength, tensile strength, elastic modulus, and permeability were assessed after 28 days of curing. Nanosilica and basalt fibers significantly enhanced mechanical performance and reduced permeability. The optimal mix (10 kg/m³ nanosilica, 2 vol.% basalt fibers) achieved 61.8 MPa compressive strength, 56.85 MPa tensile strength, 60.88 GPa elastic modulus, and 4.7 mm permeability improvements of 27%, 33.76%, 16%, and 31.88% over controls. ANOVA validated second-order models (R² > 0.97) for predictive accuracy. Sensitivity analysis identified nanosilica dosage as key for compressive strength and water-to-cement ratio for permeability. Monte Carlo simulations provided 95% confidence intervals, and benchmarking against empirical models confirmed RSM's superiority. This research ensures dimensional consistency and offers practical guidance for scalable, sustainable SCC designs, minimizing experiments and costs. https://ceij.ut.ac.ir/article_107063_02f0db501dcc445cc48e09e6d5cc1e2d.pdf