冻融环境影响下碳纤维混凝土压阻变化规律分析

Analysis of Piezoresistive Change Rules on Carbon Fibers Reinforced Concrete Under Freeze-Thaw Environments

低温对碳纤维压阻特性的智能材料监测性能影响较大。利用碳纤维混凝土试件进行快速冻融循环试验及轴向压力试验,同时按照碳纤维单丝受拉体积不变原理建立碳纤维混凝土压阻模型。通过试验和理论模型分析可知:纤维长度20 mm的碳纤维混凝土试件的抗冻性能比普通混凝土的高100%;随着冻融循环次数的增加,压力强度值逐渐减小,而电阻值先增加后减小,分界值为冻融50次;在冻融轴压耦合作用下,冻融对电阻下降的影响更大,同时碳纤维压阻试验值与理论值存在一定误差。

Low temperature had great influence on the monitoring performance of smart materials with piezo⁃resistive properties of carbon fibers.Rapid freeze-thaw cycle test and axial pressure test were carried out on carbon fibers reinforced concrete specimens,and the piezoresistance model of carbon fibers reinforced con⁃crete was established according to the principle of constant tension volume of carbon fibers.According to the test and theoretical model analysis,the freezing resistance of the 20 mm carbon fibers reinforced con⁃crete specimen is 100%higher than that of ordinary concrete.With the increase of the number of freezethaw cycles,the pressure strength value decreased gradually,while the resistance value increased first and then decreased,and the cut-off value is freeze-thaw 50 times.The effect of freeze-thaw on resistance de⁃cline is greater than that of pressure under the coupling effect of freeze-thaw axial compression.At the same time,there are some errors between the experimental and the theoretical value of the piezoresistance of carbon fibers.