I 摘要 膨胀裂缝是一种常见的由非荷载作用引起的混凝土裂缝，膨胀裂缝产生的原 因是膨胀源膨胀导致混凝土膨胀不均匀，这种不均匀性导致混凝土局部出现的拉 应力超过承受极限后，就会产生膨胀裂缝。延迟钙矾石(DEF)是一种钙矾石为膨胀 源的混凝土膨胀破坏，多发生在混凝土结构投入使用很长一段时间后，因此很难对 延迟钙矾石引起的膨胀破坏进行评估。 交流阻抗谱(ACI)是一种用交流信号来分析材料性能或者反应过程的方法，当 对一个物体施加微扰，会产生一个对应的响应，在不同频率下二者比值的复数形式 (即阻抗)组成的图谱就是交流阻抗谱。用等效电路图将阻抗谱中的信息转化成可以 量化表示的方式，就得到了混凝土的渗流结构参数（PSP）。 本文的主要目的是研究交流阻抗谱监测混凝土膨胀开裂的可行性，实现途径 是通过分析混凝土膨胀开裂过程中交流阻抗谱和渗流结构参数的变化特征，来得 出二者之间的关系。利用这种关系就能实现交流阻抗谱对混凝土膨胀开裂的监测。 如果交流阻抗谱能投入实际应用，就能对类似延迟钙矾石的混凝土膨胀开裂进行 快速无损的监测和评估。 通过向混凝土中外加膨胀组分（固硫灰，石膏），以及提供内外部条件使混凝 土出现延迟钙矾石生成现象，观测到部分混凝土中出现了膨胀和表面开裂的现象。 有表面开裂现象的混凝土阻抗谱中出现了高频半圆突变的现象，部分渗流结构参 数(r h ，R ct ，T)的走势也在开裂时间点后发生转变。这说明混凝土的膨胀开裂会对混 凝土的交流阻抗谱和渗流结构参数产生影响，混凝土开裂前后内部结构的变化是 不一样的，所以对阻抗谱和渗流结构参数的影响是不相同的。这个试验结果证明了 混凝土膨胀开裂同交流阻抗谱和渗流结构参数之间是相互联系的，理论上通过阻 抗谱和渗流结构参数来监测混凝土的膨胀开裂是可行的。 结合混凝土膨胀破坏模型，通过混凝土膨胀开裂过程中的三种效应，能间接建 立起渗流结构参数和混凝土膨胀开裂的关系，目前这种关系是模糊的，尚需要很多 探索，根据开裂混凝土阻抗谱高频半圆的突变现象，提出利用 R ct 值和高频半圆最 高点来实现对混凝土表面开裂预警。 关键词，交流阻抗谱，膨胀开裂，渗流结构，延迟钙矾石英文摘要 Ⅲ ABSTRACT Expansive crack is one of the cracks caused by non-load force, which is caused by the expansion uniformity of expansion source, expansive crack happen when the partial tensile stress exceeds the limit. Delayed ettringite formation (DEF) is a kind of concrete expansion damage of which source is ettringite in the concrete, it is difficult for damage assessment. Since DEF always occurs after concrete structures have been put into use for a long period of time. AC impedance spectroscopy (ACI) is a method of analyzing material properties or reaction process with AC signal, there will be a response when applying perturbation on an object, plural forms of the two signals (i.e. the impedance) in different frequencymake up theAC impedance spectrum. We can get the percolation structure parameters (PSP) of concrete structure when impedance spectra information is translated into a quantitative representation with equivalent circuit diagram. The purpose of this paper is to assess the feasibility of AC impedance monitoring concrete expansion and cracks, which will be proposed through the analysis of the concrete expansion characteristics, ACI and PSP of the cracking process, the monitoring can be achieved with this connection obtained via the analysis. If the ACI spectrum can be put into practical application, it will be easy to conduct fast and lossless evaluation to concrete expansion and cracks like DEF. By adding expansion component (FBC ashes, dihydrate gypsum) to the concrete, andprovidingtheinternal andexternalconditionsofDEF,expansionandsurfacecracking in some of the specimens were observed.There was a high frequencysemicircle mutation in the ACI of surface-cracked concrete, the trend of some PSPs (r h , Rct, and T) changed at the time point of cracking. It is believed that concrete cracking will both affect ACI and PSP.it is not the same effect on the ACI and PSP because the internal structure changes of concrete before and after cracking are not the same, The experimental results indicate that the concrete cracking,ACI and PSP are interrelated, it is feasible to monitor the expansion and cracking of concrete by means ofACI. According to the Model of concrete expansion and cracking, the relationship ofACI and PSP with expansion and cracking can be indirectly established through the three effects in the process of cracking, Further study is needed since the relationship is very ambiguous, according to the mutation of ACI high-frequency semicircle, the Rct value重庆大学硕士学位报告 Ⅳ and the highest point of high-frequency semicircle are considered to be applicable for early warning of the concrete surface cracking. Keywords: AC Impedance (ACI), Expansion and Cracking, Percolation Structure Parameters (PSP), Delayed Ettringite Formation (DEF)目 录 Ⅴ 目 录 中文摘要..................................................................................................................................I 英文摘要..............................................................................................................................III 1 绪 论................................................................................................................................1 1.1 混凝土常见膨胀裂缝.....................................................................................................1 1.2 国内外延迟钙矾石的研究现状 .....................................................................................2 1.3 交流阻抗谱的发展和应用 .............................................................................................5 1.4 课题研究意义和主要内容 .............................................................................................7 2 交流阻抗谱法(ACI) ..................................................................................................9 2.1 交流阻抗谱的表示方法 .................................................................................................9 2.2 电化学体系和 Randles 情形 .......................................................................................10 2.3 交流阻抗谱在混凝土体系中的表示 ...........................................................................12 2.4 渗流结构.......................................................................................................................13 3 原材料及试验方法...................................................................................................15 3.1 原材料...........................................................................................................................15 3.2 试验方法.......................................................................................................................16 3.2.1 配合比设计........................................................................................................16 3.2.2 混凝土高温养护与干湿循环............................................................................16 3.2.3 交流阻抗谱测试................................................................................................16 3.2.4 混凝土线性膨胀率测试....................................................................................18 3.2.5 X 射线衍射测试.................................................................................................18 4 混凝土快速膨胀开裂和交流阻抗谱分析...................................................19 4.1 大掺量固硫灰混凝土的膨胀开裂和交流阻抗谱监测 ...............................................20 4.2 大掺量石膏混凝土的膨胀开裂和交流阻抗谱监测 ...................................................24 4.3 渗流结构参数分析.......................................................................................................28 4.4 本章小结.......................................................................................................................33 5 混凝土 DEF 膨胀开裂和交流阻抗谱分析 ................................................35 5.1 混凝土 DEF 膨胀开裂和交流阻抗谱监测 .................................................................35 5.1.1 膨胀破坏情况....................................................................................................35 5.1.2 膨胀产物 XRD 分析..........................................................................................40 5.1.3 交流阻抗谱........................................................................................................42 5.1.4 渗流结构参数分析............................................................................................49重庆大学硕士学位报告 Ⅵ 5.2 掺加粉煤灰混凝土的膨胀开裂和交流阻抗谱监测....................................................54 5.2.1 膨胀破坏情况....................................................................................................54 5.2.2 交流阻抗谱........................................................................................................57 5.2.3 渗流结构参数分析............................................................................................62 5.3 本章小结.......................................................................................................................64 6 交流阻抗谱监测混凝土膨胀开裂的理论分析 ........................................65 6.1 渗流结构参数...............................................................................................................65 6.2 R ct 值和高频半圆最高点..............................................................................................68 6.3 本章小结.......................................................................................................................70 7 结论与展望...................................................................................................................71 7.1 结论...............................................................................................................................71 7.2 展望...............................................................................................................................72 致谢.............................................................................................................................73