Abstract: Aiming at the problem that the concrete structure is easy to crack and the durability is reduced in the cold and dry areas of Northwest China, basalt fiber with excellent mechanical properties was selected as concrete reinforcement material. The volume fraction of fiber was taken as the variable. The dynamic elastic modulus, compressive strength and flexural strength of concrete specimens with different fiber volume content (0.05%, 0.1%, 0.15% and 0.2%) under freeze-thaw action of clean water, 3%NaCl solution and 5%Na₂SO₄ solution were studied. It is found that basalt fiber effectively improves the initial flexural strength and salt frost resistance of concrete, when the fiber volume content is between 0.15% and 0.2%, the attenuation rate of dynamic elastic modulus, compressive strength and flexural strength of concrete specimens under salt frost action slow down obviously. The descending rate of mechanical properties of basalt fiber reinforced concrete in three kinds of freeze-thaw media is clean water<5%Na₂SO₄<3%NaCl. Taking the dynamic elastic modulus as the damage variable, the correlation model of concrete relative compressive strength and relative flexural strength are fitted, and the correlation of the models are good. The research results provide theoretical basis and reference for the practical application and building maintenance of basalt fiber reinforced concrete.

Key words: concrete, basalt fiber, salt freezing, mechanical property, damage degree