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首页> 外文会议>3rd International Workshop on Structural Health Monitoring, Sep 12-14, 2001, Stanford University >Fiberoptical Sensors for an In-Situ Monitoring of Moisture and pH-Value in Reinforced Concrete
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Fiberoptical Sensors for an In-Situ Monitoring of Moisture and pH-Value in Reinforced Concrete

机译：用于现场监测钢筋混凝土中的水分和pH值的光纤传感器

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Concrete is the most important material for any buildings or bridges, with widespre ad utility. The preservation of its structures is of major interest , because of many potentially destructive agents or reactants, which may be of physical or chemical nature depending on their action. Damaging chemical substances are numerous, of natural or industrial origin and they occur in the soils and water. In particular, moisture has an important influence on the lifetime of concrete structures. It is fact, that water acts as transport medium for damaging ions such as chloride, sulfate, carbonate and ammonium and as a chemical agent mobilizes corresponding acids from their salts. Thus, we developed an integrated fiberoptical sensor system, which allows an in-situ non-destructive long-term monitoring of concrete structures. As moisture indicator we have used a pyridinium-N-phenolat betaine dye, which shows a distinct solvatochromic behavior in UV-VIS measurements and 4-amino-N-methylphthalimid in its fluorescence spectra . The dyes are embedded in a polymer matrix, whose moderate polarity is enhanced by free water diffusing into the sensor. This leads to a continuously hypsochromic shift of the absorption or fluorescence spectra according to the water concentration in the matrix (up to 28 wt%). The determination of the pH-value of concrete material is of major importance for ; the assessment of acidic attacks which may lead to serious damage in reinforced concrete, as the embedded steel structures exhibit long-term stability (i.e. resistance to corrosion) only at pH-values 9 or higher. Therefore we developed a fiberoptical sensor system for the measurement of pH-values in concrete consisting of pH-indicator dyes immobilized in a highly hydrophilic polymer matrix. Any change in pH-value of the moist concrete material is indicated by a color change of the dye/polymer system. The sensor system shows long-term stability even in aggressive media of pH 12 - 13.
机译：混凝土是任何建筑物或桥梁最重要的材料，具有广泛的用途。由于许多潜在的破坏性试剂或反应物，根据其作用可能具有物理或化学性质，因此其结构的保存受到了极大的关注。破坏性化学物质数量众多，是自然或工业来源的，它们存在于土壤和水中。尤其是水分对混凝土结构的使用寿命有重要影响。实际上，水充当破坏离子（例如氯离子，硫酸根，碳酸根和铵离子）的传输介质，并充当化学剂从其盐中迁移出相应的酸。因此，我们开发了一个集成的光纤传感器系统，该系统可以对混凝土结构进行就地无损长期监控。作为湿度指示剂，我们使用了吡啶鎓-N-苯酚甜菜碱染料，该染料在UV-VIS测量中显示出明显的溶剂变色行为，在其荧光光谱中显示出4-氨基-N-甲基邻苯二甲酰亚胺。染料嵌入聚合物基体中，自由水扩散到传感器中可增强其适度的极性。这导致吸收或荧光光谱根据基质中的水浓度（高达28 wt％）连续发生变色移动。确定混凝土材料的pH值对于以下方面至关重要。评估可能会对钢筋混凝土造成严重破坏的酸性侵蚀，因为仅在pH值9或更高时，嵌入式钢结构才显示出长期稳定性（即耐腐蚀性）。因此，我们开发了一种用于测量混凝土中pH值的光纤传感器系统，该系统由固定在高度亲水的聚合物基质中的pH指示剂染料组成。湿混凝土材料的pH值的任何变化都由染料/聚合物系统的颜色变化指示。该传感器系统即使在pH 12-13的腐蚀性介质中也显示出长期稳定性。

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