Optimization of Cementitious Composites Using Response Surface Methodology: Enhancing Strength and Durability with Rice Husk Ash and Steel Fibers

Emphasizing the integration of Rice Husk Ash (RHA), steel fibers, and various water-cement ratios to generate sustainable and high-performance construction materials, this study focuses on the optimization of cementitious composites utilizing Response Surface Methodology (RSM). Twenty mix designs were experimentally evaluated to assess their effects on water absorption, flexural strength, and compressive strength. A water–cement ratio of approximately 0.35 combined with a 10–15% RHA replacement yielded compressive strengths ranging from 24.6 MPa to 40.5 MPa, which are comparable to or higher than those reported for similar sustainable concrete systems in existing literature. Flexural strength varied from 6.2 MPa to 7.8 MPa; optimum results were obtained for steel fibers with an aspect ratio of 80–100 and modest degrees of RHA. With the minimal absorption seen at balanced water-cement ratios and 10% RHA content, water absorption ranged between 5.1% and 6.5%. The value of RHA in lowering water absorption (p = .047) and enhancing strength properties was shown statistically. Surface and contour plots help one to fully understand different interactions and underline the need of parameter tuning. The findings verify the capacity of RHA and steel fibers to generate robust, low-cost, ecologically friendly composites, thereby supporting sustainable construction techniques and best use of resources.