碱环境下GFRP筋拉伸性能加速老化试验研究

Accelerated Aging Tests for Evaluations of Tensile Properties of GFRP Rebars Exposed to Alkaline Solution

基于ACI 440.3R—04规定的试验方法,开展了碱环境下玻璃纤维增强塑料(GFRP)筋拉伸性能的加速老化试验研究.试件数量共150根,试验参数包括:(1)碱溶液温度,分别为40,60,80℃;(2)GFRP筋直径,包括12.7,16.0,19.0mm;(3)碱溶液中的侵蚀时间,分别为3.65,18,36.5,92,183d.研究表明:在40,60,80℃碱溶液中侵蚀183d后,直径为16.0mm的GFRP筋的拉伸强度分别下降了34.97%,48.81%和68.85%;在60℃碱溶液中侵蚀183d后,12.7,16.0,19.0mm直径GFRP筋的拉伸强度衰减量分别为56.08%,48.81%和47.08%;随着浸泡时间的增加,40,60,80℃碱环境下GFRP筋的拉伸强度及伸长率呈下降趋势,且温度越高,衰减速率越大.采用扫描电子显微镜(SEM)对腐蚀前后GFRP筋的微观形貌进行了观测,发现腐蚀后GFRP筋的劣化区域内纤维和树脂之间的界面变得松散,纤维与周围树脂之间出现了明显的脱黏现象,而且随着碱环境温度的提高这种脱黏现象变得更为明显.最后,基于Arrhenius方程提出了碱环境下GFRP筋拉伸强度的预测模型.

According to the ACI 440.3R--04, accelerated aging tests for evaluations of tensile properties of glass fiber reinforced plastic（GFRP） rebars exposed to alkaline solution were conducted. 150 GFRP rebars were used in the test and the test parameters included： （1） temperature of alkaline solution at 40, 60 and 80 ℃ ;（2） diameters of GFRP rebar were 12.7, 16.0, 19.0 mm; （3） immersion period was 3. 65, 18, 36.5, 92, 183 d, respectively. The results show that after being exposed to alkaline environment for 183 d at 40, 60 and 80℃, tensile strength of GFRP rebars with diameter of 16.0 mm decreased by 34. 97%, 48.81 % and 68.85 %, respectively. After being exposed to alkaline environment for 183 d at 60 ;C, the attenuation value of tensile strength of GFRP rebars with diameters of 12.7, 16.0, 19.0 mm were 56.08%, 48.81% and 47.08%, respectively. With the increase of immersion period, the tensile strength and elongation of GFRP rebars exposed to alkaline environment at 40, 60, 80 ℃ decreased, and the higher the temperature, the greater the decay rate. The microstructure of the GFRP rebar surface was surveyed under scanning electron microscopy（SEM）, and it indicated that the interface between fiber and resin of GFRP rebars in the corrosion region become loose and a clear debonding phenomenon appears, with the temperature increased, the interfacial debonding of GFRP rebars become more obvious. Finally, based on the Arrhenius equation, tensile strength prediction model of GFRP rebars under alkaline environment was proposed.