Abstract: In order to study the effects of diameter and corrosion environment on the tensile properties of BFRP bars,the tensile mechanical tests of three kinds of BFRP bar specimens with different diameters (6 mm, 8 mm, 10 mm) were carried out under the natural environment, alkaline solution soaking (pH=10), ultraviolet irradiation (irradiance is 550 W/m²) and their cross corrosion environment, and scanning electron microscopy (SEM) images were used to evaluate the microstructure of BFRP bars after the fracture, and the test results were analyzed. The main conclusions are as follows: under three different environmental conditions, with the corrosion time increasing, the tensile strength of BFRP bars decreases and the degradation rate decreased gradually; the fluctuation of the elastic modulus of BFRP bars is less than 5%, but not obviously; the trend of tensile strength and elongation at break is largely the same; under the ultraviolet irradiation environment the tensile strength of BFRP bars shows the phenomenon of degradation and incomplete recovery;under the cross corrosion environment, that of 6 mm and 8 mm diameter BFRP bars shows the same law, but the 10 mm diameter BFRP bars has not. Based on the durability decay rate defined in this paper, the researchers finds that the effect of alkaline solution soaking on the durability of BFRP bars with diameters of 6 mm and 8 mm is all the largest, and that of cross corrosion environment is moderate, and that of ultraviolet irradiation environment is the least; the effect of cross corrosion environment on the durability of BFRP bars with diameters of 10 mm is the largest, and that of alkaline solution soaking is moderate, and that of ultraviolet irradiation is the least; under three different environments, the durability decay rate of 6 mm diameter BFRP bars is all the biggest, and that of 10 mm diameter BFRP bars is all the smallest.

Key words: BFRP bars, ultraviolet solution, ultraviolet light, cross-corrosion environment, SEM, decay rate of durability