ECC拉伸应变和裂缝模式对体积电阻率的影响

发布时间：2018-02-22 01:02

本文关键词： 炭黑矿渣微粉 ECC 二电极法体积电阻率自感知特性单轴拉伸试验　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：水泥基材料的压敏特性早已被研究,但由于水泥基材料的脆性导致大多研究局限于在压力荷载的作用下。工程水泥基复合材料(ECC)呈现优越的延性并同时产生众多宽度可控的微裂缝。这些力学特点为研究ECC材料在受拉和受弯状态下体积电阻率的变化提供了可能性。探究ECC自身电阻率与拉应力与拉应变的关系,以及与裂缝模式的关系,进而应用于建筑物的健康监控。相比于传统的预埋置的传感器装置,利用材料自身的电学特性侦测裂缝和拉应变具有无可比拟的优越性,因为这种新型的传感器技术并不会给建筑物本身带来不利影响,且可以监控整个建筑物,此外具有更大的应变监测范围。因此利用ECC材料发展新型的传感器就有十分重要的意义。首先,本文利用工业废料矿渣微粉(GGBS)制备ECC材料,并用适量的引气剂和橡胶粉末改善GGBS-ECC的延性。再在此基础上加入一定比例的炭黑(CB)来提高ECC材料的导电性。发现炭黑的加入会严重影响ECC的极限拉应变,通过改变水胶比、引气剂和橡胶粉末的掺量,最终得到具有较低电阻率同时相对较好延性的CB-ECC配比设计。其次,采用二电极法对不同掺量的CB-ECC进行电阻测量,发现所有试件在试验初期均出现极化现象,但物质极化随测试时间增加而逐渐趋于稳定。同时得出,增加炭黑的比例有助于降低CB-ECC的电阻率。最后,研究CB-ECC材料在单轴拉伸和四点弯曲试验下,电阻率随应变、时间的关系,以及比较在极化稳定阶段、弹性阶段、非弹性阶段和应力软化阶段的电阻率的变化。
[Abstract]:The pressure-sensitive properties of cement-based materials have long been studied. However, due to the brittleness of cement-based materials, most of the research is confined to the pressure load. The engineering cement matrix composites (ECCs) exhibit superior ductility and produce many microcracks with controllable width. These mechanical characteristics are as follows. It is possible to study the variation of volume resistivity of ECC materials under tensile and flexural conditions. The relationship between electrical resistivity and tensile stress and strain of ECC is investigated. And the relationship with crack mode, and then applied to health monitoring of buildings. Compared with the traditional pre-buried sensor device, it has unparalleled advantages to detect cracks and tensile strain by using the electrical characteristics of the material itself. Because this new sensor technology does not adversely affect the building itself and can monitor the building as a whole. Therefore, it is very important to develop a new type of sensor by using ECC materials. Firstly, the ECC materials are prepared by using industrial waste slag micro-powder (GGBs). The ductility of GGBS-ECC was improved with proper amount of air entraining agent and rubber powder, and the electrical conductivity of ECC material was improved by adding a certain proportion of carbon black. It was found that the addition of carbon black would seriously affect the ultimate tensile strain of ECC, and by changing the water-binder ratio, Finally, the ratio design of CB-ECC with lower resistivity and better ductility is obtained by adding air entraining agent and rubber powder. Secondly, the resistance of CB-ECC with different content is measured by two-electrode method. It was found that all the specimens showed polarization phenomenon at the beginning of the test, but the material polarization tended to be stable with the increase of test time. At the same time, it was found that increasing the proportion of carbon black would help to reduce the resistivity of CB-ECC. The relationship of resistivity with strain and time in uniaxial tensile and four-point bending tests of CB-ECC materials is studied. The changes of resistivity in polarization stable stage, elastic stage, inelastic stage and stress softening stage are compared.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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