Abstract: In order to study the mechanical properties of shotcrete with different basalt fiber (BF) lengths in different age, experimental results of different working conditions under same amount of fibers with different lengths are compared. The basic mechanical properties at different ages and the development law of basalt fiber concrete are explored. The results show that: (1) All of the three kinds of BF length (6, 16 and 50 mm) can improve the compressive strength and splitting tensile strength of shotcrete, and with faster growth in the early stage, and slower growth in the later stage, strength improving effect varys with lengths. (2) According to comprehensive evaluation, the order of strength is BF16＞BF50＞BF6. (3)Through curve fitting analysis, the compressive strength and splitting tensile strength of BF concrete satisfies the relationship of formula y=a×xb. (4) The shear strength of concrete presents obvious stage characteristics in different age with three different BF lengths, and BF has negative effect on the shear strength of shotcrete. (5)In bending toughness test, the initial cracking load of BF shotcrete is improved, but there is no obvious postcracking toughness. (6) The initial cracking load of concrete does not change obviously with the length of BF, and 16 mm is the optimal BF length.

Key words: basalt fiber, concrete, mechanical properties, age, fiber length