For advanced technical applications, environmentally-neutral basalt fiber reinforced epoxy (BF/Ep) composites hold promise as they combine the strength, durability, and environmental benefits of basalt fibers with the toughness and adaptability of epoxy. The mechanical characteristics and fractography of epoxy-based composites with and without plain weave basalt fiber mats treated with silane are investigated in this work. The composites were produced by hand-laying up and hot pressing. Untreated and silane-treated BF/Ep samples were subjected to mechanical tests, including microstructure, hardness, tensile, short beam, flexure, and impact, in compliance with ASTM guidelines. Mechanical property studies revealed that the silane-treated BF/Ep composites had a substantially higher mechanical strength than the untreated BF/Ep composites. Maximum tensile strength (276.8 ± 6.3 MPa), interlaminar shear strength (33 ± 2.0 MPa), flexural strength (289.2 ± 9.5 MPa), impact strength (170.4 ± 2.5 J), and Rockwell hardness (124 ± 2) were found for the silane-treated BF-Ep composite samples. In terms of microhardness, tensile strength, interlaminar shear strength, flexural strength, and impact strength, the epoxy composite treated with silane and containing 60% BF mats was the best. Thus, in addition to other functions provided by either BFs or the epoxy matrix, the addition of high mass fractions of BF mats to an epoxy matrix may be advantageous for applications needing superior mechanical properties. Moreover, fractographic analysis showed that the fiber/matrix adhesion was comparatively weaker, which made it a preferred location for crack nucleation. Additionally, there was proof that the silane-treated fiber had cracked arrest above 55 wt. %.
