腐蚀及高温后BFRP筋力学性能研究

Mechanical properties of BFRP bars after corrosion and high temperature

为了研究腐蚀和高温对玄武岩增强纤维复合材料(BFRP)筋形貌和力学性能的影响,采用酸碱加速腐蚀和高温炉加热方法对BFRP筋进行了损伤试验,利用拉伸试验、抗压试验和压式剪切试验对不同损伤BFRP筋进行了力学性能测试。结果显示:BFRP筋在pH=3的溶液中长期腐蚀会出现表面颜色变黑、体积膨胀和树脂基体脱落等现象,腐蚀45 d后抗拉、抗压及抗剪强度分别退化了35.26%、44.75%和23.89%;BFRP筋在碱性溶液中长期腐蚀后颜色无明显变化,有白色泡沫状反应物产生,表面局部出现蚀坑;在pH=13的溶液中腐蚀45 d后抗拉、抗压及抗剪强度分别退化了35.69%、37.84%和40.12%;温度由70℃增加到350℃后,BFRP筋的树脂基体逐渐碳化,抗拉、拉压及抗剪强度分别退化了89.43%、77.75%和58.51%。由此可知:随腐蚀损伤增加,BFRP筋的抗拉、抗压、抗剪强度呈减小趋势,抗拉强度受腐蚀影响最大;BFRP筋的基本力学性能参数在150℃以下高温后退化率未超过10%,150℃~300℃高温后退化率超过50%,300℃~350℃高温后退化率急剧增加至80%;150℃~300℃高温后BFRP筋的力学性能参数值需要折减,300℃高温后BFRP筋不建议使用。

The influence of corrosion and high temperature on the morphology feature and mechanical properties of BFRP bar was studied in this paper.Acid-based accelerated corrosion and high temperature furnace heating method were adopted to conduct damage test.Meanwhile,the mechanical properties of BFRP bars with different damage degrees were tested through tensile test,compression test and compression shearing test.Darken surfaces,dilated volume and shed resin matrix of BFRP bars were observed on a long term corrosion in pH=3 solution,and the tensile strength,compression strength and shear strength deteriorated by 35.26%,44.75%and 23.89%after a 45 d corrosion;No significant change in color was observed on a long term corrosion when BFRP bars were steeped in alkaline solution,whereas local corrosion pits were induced by white foam reactants,and the tensile strength,compression strength and shear strength deteriorated by 35.69%,37.84%and 40.12%after a 45 d corrosion in pH=13 solution;The resin matrix of BFRP bars gradually carbonized on a temperature rise from 70℃to 350℃,and the tensile strength,compression strength and shear strength deteriorated by 89.43%,77.75%and 58.51%.To sum up,the tensile strength,compression strength and shear strength of BFRP bars decrease with the increase of damage degree,and the tensile strength is significantly affected;The degradation rate of BFRP fundamental mechanical properties is below 10%under 150℃,and it exceeds 50%when the temperature reaches to 150℃~300℃.And the rate exponentially increases to 80%when the temperature reaches to 300℃~350℃;A reduction of mechanical properties parameter values is required when the temperature is 150℃~300℃,and BFRP bars are not recommended to be employed when the temperature is above 300℃.