湿热酸雨环境对CFRP-混凝土界面剪切粘结性能影响

Effect of hot and humid acid rain environment on shear bond properties of CFRP-concrete interface

为研究湿热酸雨环境对碳纤维增强树脂复合材料(CFRP)-混凝土界面剪切粘结性能影响,设计并制作了45个CFRP-混凝土单剪试件,采用机械高温干湿循环和人工配制pH为1.5的酸雨溶液来模拟湿热酸雨环境,通过开展CFRP-混凝土切向剪切试验,分析了混凝土强度和腐蚀次数对界面破坏模式、剥离承载力、极限位移、荷载-位移曲线和粘结区间应变分布的影响,建立了基于湿热酸雨影响系数的界面本构关系模型,并提出了湿热酸雨环境腐蚀程度划分参考方法。研究结果表明:随着混凝土强度提高,界面粘结性能增强,界面剥离位置逐步向胶层处变化;随着腐蚀次数增长,界面粘结性能呈现先升高后降低的变化趋势,3种强度混凝土对应界面剥离荷载和极限位移分别比未受到腐蚀的试件提升3.04%、3.50%、5.78%和0.50%、0.49%、0.95%,酸雨中SO_(4)^(2-)离子侵入混凝土表层生成膨胀性物质CaSO_(4)·2H_(2)O,会导致腐蚀前期界面粘结性能暂时增强;切向剪切试验中荷载-位移曲线呈现上升、震荡、加强和下降4个阶段;粘结区间上应力传递方向为从加载端传递至自由端;文中提出基于湿热酸雨影响系数的界面本构关系模型,与现有试验数据吻合度较好,且精度较高,偏于安全。相关研究成果可为高湿高热酸雨地区CFRP加固工程提供理论支撑和设计指导。

In order to study the influence of hot and humid acid rain environment on the shear bond performance of carbon fiber reinforced polymer(CFRP)-concrete interface,45 CFRP concrete single shear specimens were designed and manufactured.The hot and humid environment was simulated by mechanical high temperature dry and wet cycles and manually configured acid rain solution with pH 1.5.Through CFRP concrete shear tests,the effects of concrete strength and corrosion times on the interface failure mode,peel bearing capacity,ultimate displacement,load displacement curve and strain distribution in the bonding zone were discussed,an interfacial constitutive model based on the influence coefficient of hot and humid acid rain was established,and the reference method for the division of corrosion degree in hot and humid acid rain environment was proposed.The results show that with the increase of concrete strength,the interface bonding performance is enhanced,and the interface peeling position gradually changes to the adhesive layer.With the increase of corrosion times,the interfacial bonding performance presents a trend of increasing first and then decreasing.The corresponding interfacial peel bearing load and ultimate displacement of the three strength concretes are 3.04%,3.50%,5.78%and 0.50%,0.49%,0.95%higher than those of the uncorroded specimens,respectively.SO_(4)^(2–)ions in acid rain invade the concrete surface to generate expansive material CaSO_(4)·2H_(2)O,which will temporarily enhance the interfacial bonding performance in the early stage of corrosion.In the tangential shear test,the load displacement curve presents four stages:Rising,concussion,strengthening and falling.The direction of stress transfer in the bonding zone is from the loading end to the free end.The interfacial constitutive model of the influence coefficient of hot and humid acid rain proposed in this paper is in good agreement with the existing test data,with high accuracy and safety.The related research results can provide theoretical support and design guidance for CFRP reinforcement project in high humidity and high heat acid rain area.