碳纤维及碳纤维布混凝土抗冻性及能量耗散试验研究

Experimental study on frost resistance and energy dissipation of carbon fiber and carbon fiber cloth concrete

为探究碳纤维增强方式对混凝土材料抗冻性能及能量耗散影响规律,利用纵波波速仪以及电液伺服压力机获取冻融循环作用(0,25,50,75,100次)后四种混凝土(素混凝土、碳纤维混凝土、碳纤维布混凝土、碳纤维及碳纤维布混凝土)的纵波波速及力学性能,分析碳纤维增强方式、冻融循环次数对试件相对动弹性模量、峰值应力、能量耗散及损伤度影响规律。结果表明:①相较于冻融循环0次素混凝土,冻融循环25,50,75,100次试件相对动弹性模量降幅分别为8.21%、18.33%、30.44%、45.89%,冻融循环次数的增加使试件相对动弹性模量降低,碳纤维及碳纤维布均能减缓试件相对动弹性模量降幅;②冻融循环次数的增加使四种不同混凝土试件峰值应力均呈降低趋势,碳纤维及碳纤维布不仅能够增强试件强度,还能够增强其抗冻性,且两者组合时对试件的提升效果最佳;③相较于未冻融试件,冻融循环25,50,75,100次时弹性变形能降幅分别为3.87%、7.63%、9.67%、12.70%,耗散能降幅分别为10.42%、21.97%、30.16%、41.60%,冻融作用会使试件内部产生损伤,降低试件储能、耗能效果;④三种碳纤维混凝土在达到峰值应力时对应机械损伤度值显著高于素混凝土对应机械损伤度值,碳纤维的增强作用能够有效提升混凝土材料吸能效果、延展性及抗冻性。

In order to investigate the effect of carbon fiber reinforcement on the frost resistance and energy dissipation of concrete materials,the longitudinal wave velocity and mechanical properties of four kinds of concrete(plain concrete,carbon fiber concrete,carbon fiber concrete,carbon fiber concrete and fiber fabric concrete)after freeze-thaw cycles(0,25,50,75,100 times)were obtained by using a longitudinal wave tachometer and an electro-hydraulic servo press.The effects of carbon fiber reinforcement method and number of freeze-thaw cycles on relative dynamic elastic modulus,peak stress,energy dissipation and damage degree were analyzed.The results show that:①Compared with plain concrete with 0 freeze-thaw cycles,the relative dynamic elastic modulus of specimens with 25,50,75 and 100 freeze-thaw cycles decreased by 8.21%,18.33%,30.44%and 45.89%.The more freeze-thaw cycles occurred,the more significant the relative dynamic elastic modulus of specimens declined.Carbon fiber and carbon fiber cloth could both slow down the relative dynamic elastic modulus of specimens.②As the number of freeze-thaw cycles increased,the peak stress of the four different concrete specimens showed a decreasing trend.Carbon fiber and carbon fiber cloth could not only enhance the strength of the specimens,but also enhance their freeze-resistance,and the combination of the two had the best lifting effect on the specimens.③Compared with the non-freeze-thaw specimens,the elastic deformation energy decreased by 3.87%,7.63%,9.67%and 12.70%,and the dissipative energy decreased by 10.42%,21.97%,30.16%and 41.60%,respectively,during freeze-thaw cycles of 25,50,75 and 100 times.The internal damage of the specimens was caused by freeze-thaw action,reducing the effect of sample energy storage and energy consumption.④The corresponding damage value of the three kinds of carbon fiber concrete at the peak stress is significantly higher than that of plain concrete,and the strengthening effect of carbon fiber can effectively improve the energy absorption effect,ductility and frost resistance of concrete materials.