摘要
为预防地铁运营产生的杂散电流对混凝土结构造成腐蚀损伤,制备出28 d电阻率大于3 kΩ/m且抗压强度大于120 MPa的地铁工程用高阻抗超高性能混凝土(HI-UHPC),通过交流阻抗谱揭示了不同因素对HI-UHPC交流阻抗性能的影响,最终提出了适用于HI-UHPC的等效电路模型。结果表明:钢纤维和PVA乳胶粉的掺入可显著提高HI-UHPC的抗压强度。普通水泥基材料的高频弧在水化10 h时出现,HI-UHPC的高频弧则在水化1 h时出现。钢纤维会使HI-UHPC内部形成钢纤维搭接而成的导电通道,增加自由电子转移的可能并降低基体体积电阻。PVA乳胶粉在HI-UHPC内部会形成基体-PVA乳胶粉膜界面并改变孔结构,减少其内部的有效导电路径,最终提高HI-UHPC的阻抗。HI-UHPC的等效电路模型由连通导电路径、不连通导电路径以及绝缘路径组成。随着龄期的增长,水化产物和聚合物膜逐渐形成,基体内自由水被消耗,孔隙结构逐渐致密,导致孔隙中载流子的传输通道被阻断,使得连通导电通道的电阻和非连通导电通道的电阻逐渐变大,而非连通导电通道的电容和绝缘导电基体的电容逐渐减小。
In order to prevent and control the corrosion damage of concrete structure caused by the stray current generated of metro operation,a high-impedance and ultra-high performance concrete(HI-UHPC)with 28-day resistivity of greater than 3 kΩ/m and compressive strength of greater than 120 MPa was prepared for subway engineering.The parameter influences on the alternating current(AC)impedance performance of HI-UHPC were investigated by AC impedance spectroscopy.An equivalent circuit model suitable for HI-UHPC was proposed.The results show that the compressive strength of HI-UHPC can be improved by adding steel fiber and PVA emulsion powder.The high-frequency arc of ordinary cement-based materials appears at 10-h hydration,while that of HI-UHPC appears at 1-h hydration.The addition of steel fiber can form the conductive channels via overlapping steel fiber in HI-UHPC,increase a possibility of free electron transfer and reduce the volume resistance of the matrix.When PVA emulsion powder is added into HI-UHPC,the interface between the matrix and PVA emulsion powder film is formed,changing the pore structure,reducing the effective conductive path in the interior of HI-UHPC,and ultimately improving the impedance performance.The equivalent circuit model of HI-UHPC consists of connected conductive path,disconnected conductive path and insulated path as well.As the ages increase,the hydration products and polymer films gradually form,the free water in the matrix consumes,and the pore structure becomes dense,leading to the blocking of the carrier transport channels in the pores.The resistance of connected conductive channel and the resistance of unconnected conductive channel increase,while the capacitance of unconnected conductive channel and the capacitance of insulating conductive matrix decrease.
作者
何倍
陈庆
何丽
宋法成
蒋正武
HE Bei;CHEN Qing;HE Li;SONG Facheng;JIANG Zhengwu(Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education,School of Materials Science and Engineering,Tongji University,Shanghai 201804,China)
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2022年第2期492-502,共11页
Journal of The Chinese Ceramic Society
基金
国家重点研发计划项目(2018YFC0705404)
国家自然科学基金资助项目(51878480,52078369)
中央高校基本科研业务费专项资金资助
关键词
高阻抗
超高性能混凝土
交流阻抗谱
等效电路模型
high impedance
ultra-high performance concrete
alternating current impedance spectrum
equivalent circuit model
