Experimental study and mechanism analysis on basic mechanical properties of basalt fiber reinforced concrete

In order to comprehensively examine the influence of basalt fiber on the basic mechanical properties of concrete, the axial compression, axial tension and direct shear tests were carried out on basalt fiber reinforced concrete (BFRC) with different fiber contents and fiber lengths. The failure modes and stress-strain curves under different loading modes were obtained from the test data, and the basic mechanical parameters of BFRC were extracted from the curves. Based on the results, the following conclusions were drawn. With the increase of fiber content, both the compressive strength and tensile strength showed an upward trend first followed by a downward trend. In general, the shear strength of BFRC was lower than that of ordinary reinforced concrete with no fiber (RC). All BFRC specimens had an increased peak strain and significantly improved deformability compared to RC. Based on a comprehensive analysis, the specimen with a fiber content of 0.2% and a fiber length of 6 mm (BFRC-0.2%-6) exhibited the best mechanical properties. In addition, mathematical regression analysis was performed on the normalized stress-strain curves of BFRC, and the influencing parameters model of basalt fiber was proposed based on the fiber content and fiber length. Moreover, scanning electron microscopy (SEM) and computed tomography were utilized to analyze the influencing mechanism of basalt fiber content and fiber length on the mechanical properties of concrete from the microcosmic and mesoscopic perspectives.