Exploring the Enhanced Dispersibility of Silane Coupling Agent–Modified Basalt Fiber and Its Impact on Concrete Mechanical Properties

In this study, silane coupling agent (KH-550) was employed to modify the surface of basalt fibers (BF) within concrete matrices, with the intent of optimizing interfacial adhesion and enhancing dispersion properties. The condition of the fiber surface was investigated using scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), and Fourier transform infrared (FTIR) techniques. The degree of BF dispersal in a concrete mixture was investigated using dispersion testing, the water washing method, and image analysis techniques. Furthermore, the impact of modified BF on the mechanical properties of concrete was evaluated. The findings suggest that both an increase in surface roughness and the presence of –NH2 significantly enhance the hydrophilicity of BF. Variance analysis reveals that the time modification parameter primarily influences the dispersivity of BF, followed by concentration and temperature. By utilizing optimum parameters: time (12 h), concentration (8 mol/L), and temperature (40°C), we obtained BF with exceptional dispersion, a fiber dispersion degree of 82% and a dispersion coefficient of 0.88. Additionally, when compared with the original fibers, the modified ones exhibited a noticeable rise in the compressive strength, flexural strength, and impact toughness of the reinforced concrete. Enhanced interfacial adhesion with the concrete matrix was also observed. These improvements were associated with alterations in the BF surface state and effective dispersivity.