碳纤维水泥砂浆柱体轴压下力电性能尺寸效应研究

Size Effect of Electrical Properties of Carbon Fiber Reinforced Mortar Prism under Axial Pressure

采用54个3种尺寸的几何相似碳纤维水泥砂浆试样,在给定电压下测试柱体电极间的电流;测试轴向应变下电阻率和柱体的极限荷载,分析给定应力下试件的灵敏度系数,计算轴压下柱体的抗压强度。研究表明:碳纤维水泥砂浆棱柱体具有压敏特性,可以利用电阻变化率来监控构件的自损伤;碳纤维水泥砂浆棱柱体的电阻率随着试件尺寸的增大而减小,即试样的电阻率存在尺寸效应现象;碳纤维水泥砂浆棱柱体试件在单向加载作用下试样的灵敏度系数随尺寸的增大而增大;抗压强度随着试件几何尺寸的增加而降低,可以用Bazant的尺寸效应律来拟合。

The 54 geometrically similar carbon fiber reinforced mortar prism specimens are adopted and electri-cal current at given voltage,electrical volume resistivity under axial strain,extreme load are tested.The gauge factor（fractional change in resistance per unit strain）at a given stress is analyzed and the strength of mortar prism specimen is calculated.The experimental results show that carbon fiber reinforced mortars have compres-sion sensibility and the change rate of electrical volume resistivity can be used as a self-diagnosis indicator of damage.The resistivity of carbon fiber reinforced mortar prism decreases with specimen size,and size effect of electrical volume resistivity exists.The gauge factor of carbon fiber reinforced mortar prisms increases with the specimen size.The strength of specimen under axial pressure decreases with its size,experimental result of strength has a good agreement with Bazant size-effect law.