Study on the Influence of Fiber Parameters on the Mechanical Properties of Self-Compacting Concrete

To address the issues of significant brittleness in self-compacting concrete (SCC), limited parameter ranges in existing steel fiber reinforcement studies, and incomplete performance evaluation systems, this study conducted mechanical performance tests on steel fiber-reinforced SCC (SFRSCC) with a wide range of volume fractions (1–3%) and multiple aspect ratios. A multi-indicator comprehensive evaluation model of compressive strength, flexural strength, and elastic modulus was established using an improved entropy-weighted TOPSIS method. Gray relational analysis was integrated to reveal nonlinear correlation patterns between fiber parameters (the volume fraction and aspect ratio) and mechanical responses. The experimental results demonstrated the following: (1) At a 3% fiber content, compressive and flexural strengths increased by 25.7% and 280%, respectively, compared to the control group; (2) the elastic modulus peaked at 2% fiber content, with excessive content (3%) causing an uneven fiber dispersion and diminishing performance gains; (3) short fibers (6 mm) achieved optimal compressive strength at 3% content and medium-length fibers (13 mm) significantly enhanced flexural strength, while long fibers (25 mm) maximized the elastic modulus at 2% content. The combined application of the improved entropy-weighted TOPSIS method and gray relational analysis identified that the high fiber content (3%) paired with medium-length fibers (13 mm) optimally balanced flexural strength and toughness, providing theoretical guidance for the application of SFRSCC in tensile- and crack-resistant engineering projects.