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参照ACI 440.3R-04提供的试验方法,将90根玻璃纤维增强塑料(GFRP)筋分别放入40℃、60℃和80℃的模拟混凝土溶液中进行加速老化试验,侵蚀时间分别为3.65 d、18.0 d、36.5 d、92.0 d和183.0 d,分析了温度、侵蚀时间、SiO2含量等参数对GFRP筋受压力学性能的影响。研究表明:侵蚀183.0 d后,40℃、60℃、80℃模拟混凝土环境下的GFRP筋抗压强度较侵蚀前分别下降了29.59%、39.12%和47.62%,其抗压弹性模量分别下降了10.12%、12.47%和19.06%。采用扫描电子显微镜(SEM)对侵蚀前后GFRP筋的微观形貌进行了观测,发现侵蚀后GFRP筋的劣化区域内纤维与周围树脂之间出现了明显的脱粘现象,而且随着温度的提高这种脱黏现象更加明显。采用X射线荧光光谱分析仪(XRF)分析了侵蚀前后GFRP筋的SiO2含量变化,结果表明随着侵蚀时间的增加,模拟混凝土环境下GFRP筋中SiO2含量呈递减趋势;侵蚀前GFRP筋中SiO2含量为62.11%,在40℃、60℃和80℃模拟混凝土环境下侵蚀183.0 d后,GFRP筋中SiO2含量较侵蚀前分别下降到52.05%、50.66%和47.65%。基于XRF分析提出了模拟混凝土环境下GFRP筋抗压强度的预测模型。
According to the test method provided in ACI 440.3R-04, 90 glass fiber reinforced plastic (GFRP) bars were placed in simulated concrete solutions at 40 ℃, 60 ℃ and 80 ℃ respectively for accelerated aging test, with the erosion times of 3.65 d, 18.0 d, 36.5 d, 92.0 d and 183.0 d respectively. The effects of temperature, erosion time and SiO2 content on the mechanical properties of GFRP tendons were investigated. The results show that the compressive strength of GFRP bars under simulated concrete environment of 40 ℃, 60 ℃ and 80 ℃ decreased by 29.59%, 39.12% and 47.62%, respectively, and their compressive elastic modulus decreased by 183.0 d 10.12%, 12.47% and 19.06% respectively. Scanning electron microscopy (SEM) was used to observe the microstructure of GFRP tendons before and after erosion. It was found that there was a clear debonding phenomenon between the fibers and the surrounding resin in the deteriorated region of the GFRP tendon after erosion, and as the temperature increased Kind of sticky phenomenon is more obvious. The X-ray Fluorescence Spectrometer (XRF) analyzes the change of SiO2 content of GFRP bars before and after erosion. The results show that with the increase of erosion time, the content of SiO2 in GFRP tendons decreases with the increase of erosion time. The content of SiO2 Was 62.11%. After 183.0 d of erosion in simulated concrete at 40 ℃, 60 ℃ and 80 ℃, the content of SiO2 in GFRP tendons decreased to 52.05%, 50.66% and 47.65% respectively compared with that before erosion. Based on XRF analysis, a prediction model of compressive strength of GFRP bars simulated in concrete environment was proposed.