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首页> 外文会议>3rd International Workshop on Structural Health Monitoring, Sep 12-14, 2001, Stanford University >Microwave Near-Field Evaluation of the Effects of Cyclical Chloride Exposure and Compressive Loading on Mortar
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Microwave Near-Field Evaluation of the Effects of Cyclical Chloride Exposure and Compressive Loading on Mortar

机译：微波近场评估环氯化物暴露和压缩载荷对砂浆的影响

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Corrosion of steel reinforcement in concrete structures can be induced by the presence of chloride. Corrosion of steel rebar is a problematic infrastructure issue as it compromises the strength and integrity of the structure. Although techniques exist for chloride detection and its migration into the structure, they arc often destructive, time consuming and cannot be used for the interrogation of large surfaces. In recent years, characterization and testing of cement-based structures has been performed using near-field microwave nondestructive testing techniques. These techniques have employed open-ended rectangular waveguide probes as well as embedded monopole probes. In a recent investigation, it was shown that near-field detection and evaluation of chloride content, present in the mixing water, in cement paste and mortar arc possible at 10 GHz (X-band) and 3 GHz (S-band). It has also been shown that the presence of chloride in mortar specimens periodically exposed to chloride solution can be detected using these techniques. In the present experiment cubic (8"x 8"x8") mortar specimens were produced with water-to-cement (w/c) ratio of 0.5 and sand-to-cement (s/c) ratio of 2.5 using ASTM type Ⅰ/Ⅱ Portland cement. Since the field exposure to chloride is cyclical in nature, these specimens were cyclically exposed to chloride bath. To further simulate the real environment and also to promote penetration of chloride in mortar specimen, in the present investigations these specimens are also put under compression loading before exposure to chloride bath. Daily near-field microwave reflection and dielectric property measurements were conducted on these specimens, at S-band (3 GHz) and X-band (10 GHz), after they were taken out of the chloride bath and until they became mostly devoid of free water. This paper presents the results of these measurements (at S-band) as well as a discussion of the findings.
机译：氯化物的存在会引起钢筋混凝土结构中的腐蚀。钢筋的腐蚀是一个有问题的基础设施问题，因为它损害了结构的强度和完整性。尽管存在用于氯化物检测及其向结构中迁移的技术，但它们通常具有破坏性，耗时且不能用于大型表面的询问。近年来，已使用近场微波无损检测技术对水泥基结构进行了表征和测试。这些技术已经采用了开放式矩形波导探头以及嵌入式单极探头。在最近的一项研究中，表明在10 GHz（X波段）和3 GHz（S波段）下，水泥浆和砂浆电弧中混合水中存在的氯含量的近场检测和评估是可能的。还表明，使用这些技术可以检测到定期暴露于氯化物溶液的砂浆样品中氯化物的存在。在本实验中，使用ASTMⅠ型生产立方（8“ x 8” x8“）砂浆样品，水灰比（w / c）为0.5，砂灰比（s / c）为2.5。 /Ⅱ硅酸盐水泥：由于氯化物在自然界中是周期性暴露的，因此这些标本周期性地暴露在氯化物浴中，为进一步模拟真实环境并促进氯化物在砂浆标本中的渗透，在目前的研究中，这些标本也是在暴露于氯化物浴之前，将其置于压缩载荷下，然后从S波段（3 GHz）和X波段（10 GHz）对这些样品进行每日近场微波反射和介电性能测量。氯浴，直到它们几乎没有水为止，本文介绍了这些测量结果（在S波段）以及对发现的讨论。

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