Abstract: The purpose of this paper is to study the effect of basalt fiber at the contents of 0.05%~0. 35%on compressive strength , splitting tensile strength and bending performance of concrete .Scanning electron microscope ( SEM ) is used to analyze the microscopic mechanism of basalt fiber-reinforced concrete.The results show that 3 d, 7 d and 28 d compressive strength and tensile strength of concrete have been improved to varying degrees when the fiber content is less than 0.3%.When the content of basalt fiber exceeds 0.3%,28 d compressive and tensile strength of concrete began to decline ,and the greater the content of fiber , the more strength decline .Bending test results show that the flexural strength of concrete increase by an average of 7.96%when the content of basalt fiber increases from 0.05%to 0. 25%, and the flexural strength of concrete increase by 17% when content is 0 .2%.and after the incorporation of basalt fiber , stress-strain curve for concrete have a well-marked yield point , ultimate tensile strain of concrete increases , the elastic modulus decreases , implying a decrease in the rigidity .On the other hand , Adding basalt fiber to concrete can improve ductility and flexibility of concrete , increase the crack resistance of concrete and extend the service life of concrete .

Key words: basalt fiber;concrete;mechanical property