导电水泥基材料力—电和机敏性能研究

发布时间：2018-05-04 05:00

  本文选题：导电水泥基材料 + 力学性能　； 参考：《南京航空航天大学》2017年硕士论文

【摘要】：建筑工程在服役过程中,受到外部荷载的作用会产生损伤和承载力下降等问题,易引起突发性事故。因此,实时监测这些工程材料的损伤程度有很大价值。传统的监测方法主要有内置传感器,但该方法造价高、耐久性能差、对使用环境限制较多,阻碍和影响了该方法的建设应用。导电水泥基材料就是在水泥基材料中掺具有导电性的功能材料,通过在内部形成连续的导电网络,使其具备感应自身变形和损伤的功能,为实时监测结构内部损伤及使用状态提供了新的可能性。本文研究了导电水泥基材料的力-电及机敏性,具体研究内容及结论如下:研究了掺不同功能材料对水泥浆体、砂浆导电性能的影响。水泥浆体电阻率随功能材料掺量增大而减小,功能材料C水泥浆体渗流阈值约为1.0%,功能材料G水泥浆体渗流阈值约为10%,功能材料G替代功能材料C时,水泥浆体28d电阻率随替代比例的增大先减小再增大再减小再增大;改性导电水泥浆体的电阻率随聚灰比增大而增大,力学性能随聚灰比的增大先增大后减小;水泥砂浆中功能材料G替代功能材料C的最佳比例约为25%,改性导电水泥砂浆最佳聚灰比为0.02。研究了掺功能材料C和G混凝土的机敏性。混凝土试样在受压过程中随压力增大,试块的电阻率呈现下降、平衡和剧增三个阶段,反映混凝土内部结构缺陷裂纹闭合、裂纹产生和破坏;混凝土掺入聚合物后平衡阶段增长,说明掺聚合物可抑制混凝土新裂缝的产生;循环荷载下,在每个周期的加压阶段混凝土电阻率持续减小,卸载后电阻率增大,每个循环内的变化规律基本一致;掺0.75%功能材料C和2.5%功能材料G的导电混凝土受弯机敏性较好,电阻变化率达到8.60%。用ANSYS模拟掺功能材料导电混凝土的温度场分布,可知温度由中心位置向四周逐渐降低,中心位置温度高达47.36℃,边缘角点位置为41.72℃;对比试验结果与模拟结果,间接证明了该分析方法的适用性;模拟分析了导电混凝土在加热过程中的变形和应力应变,混凝土的变形主要是从中心位置呈环状向四周逐渐增大,最大变形出现在四个角点的位置,为0.13mm,最小变形位于上表面中心位置,为0.89×10~(-3)mm。
[Abstract]:In the service process of building engineering, damage and bearing capacity will be decreased due to external load, which can easily lead to sudden accidents. Therefore, it is of great value to monitor the damage degree of these engineering materials in real time. The traditional monitoring methods mainly have built-in sensors, but this method has high cost, poor durability, and has a lot of limitations on the use of the environment, which hinders and affects the construction and application of the method. Conductive cement-based material is a kind of functional material with electrical conductivity, which can induce its own deformation and damage by forming a continuous conductive network inside the material. It provides a new possibility for real-time monitoring of internal damage and operating state of the structure. In this paper, the mechano-electric and smart properties of conductive cement-based materials are studied. The specific contents and conclusions are as follows: the effects of different functional materials on the conductive properties of cement paste and mortar are studied. The resistivity of cement paste decreases with the increase of the content of functional material. The percolation threshold of functional material C cement paste is about 1.0 and that of functional material G cement paste is about 10. When the functional material G replaces the functional material C, the cement paste resistivity decreases with the increase of the content of the cement paste. The resistivity of the modified conductive cement paste first decreases and then decreases and then increases with the increase of the substitution ratio, and the resistivity of the modified conductive cement paste increases with the increase of the cement aggregate ratio, and the mechanical properties increase first and then decrease with the increase of the aggregate cement ratio. The optimum ratio of functional material G to functional material C in cement mortar is about 25 and the optimum cement cement ratio of modified conductive cement mortar is 0.02. The cleverness of concrete mixed with functional materials C and G was studied. The resistivity of concrete specimen decreases, equilibrium and sharp increase with the increase of pressure, which reflects the crack closure, crack generation and failure of concrete internal structure. The increase of equilibrium stage after adding polymer into concrete shows that polymer admixture can restrain the occurrence of new cracks in concrete, and under cyclic load, the resistivity of concrete decreases continuously at the compression stage of each cycle, and increases after unloading. The flexural sensitivity of conductive concrete mixed with 0.75% functional material C and 2.5% functional material G is good, and the change rate of resistance is 8.60%. The temperature field distribution of conductive concrete doped with functional materials is simulated by ANSYS. The temperature decreases gradually from the center position to the surrounding direction, the central temperature reaches 47.36 鈩，

本文编号：1841690