碱溶液、紫外线及其交叉环境下BFRP筋耐久性能试验研究

为研究直径和腐蚀环境对BFRP筋拉伸力学性能影响,开展了三种直径(6 mm、8 mm、10 mm)BFRP筋试件在自然环境、碱溶液环境(pH=10)、紫外线照射环境(辐照度为550W/m~2)及两种腐蚀环境交叉作用下拉伸试验,采用扫描电子显微镜(SEM)对BFRP筋拉伸断裂进行了分析,并对试验结果进行了研究。主要结论如下:三种不同环境作用下,随着腐蚀时间延长,BFRP筋抗拉强度减小且强度退化率逐渐下降,BFRP筋弹性模量上下波动均不超过5%,且无明显规律,断裂伸长率变化趋势与拉伸强度基本相同;紫外线环境下BFRP筋抗拉强度有退化和不完全恢复现象;交叉环境下直径分别为6 mm和8 mm BFRP筋抗拉强度也有退化和不完全恢复现象,10 mm BFRP筋则没有。基于本文所定义的耐久性衰减速率,对直径分别为6mm和8 mm BFRP筋耐久性的影响,碱环境最大,交叉环境居中,紫外线环境最小;对10 mm BFRP筋耐久性的影响,交叉环境最大,碱环境居中,紫外线环境最小。三种不同环境作用下,直径为6 mm BFRP筋耐久性衰减平均速率均最大,直径为10 mm的测试结果均最小。

EXPERIMENTAL STUDY ON THE DURABILITY OF BFRP BARS UNDER THE ENVIRONMENT OF ALKALINE SOLUTION,ULTRAVIOLET LIGHT AND THEIR CROSS CORROSION

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.