The steel-plate bonding method used to reinforce concrete slabs in bridges has a long record of adoption, and has played an important role for many years. Favorable conditions have been observed with this method in periodic inspections; however, as part of durability tests, decreases in strength of the epoxy resin adhesive (which is one of its component materials) have been observed following over time outdoor exposure under standard environmental conditions. Investigations into the causes of decreased strength of epoxy resin adhesive are useful for increasing long-term durability in future infrastructure maintenance. The estimation of environmental factors that incorporate exposure conditions and the results of conducting accelerated tests revealed that the performance of epoxy resin adhesive was influenced by humidity. Additionally, decreases in strength accompanying reaction progress of epoxy resin were also observed. These results indicate that the degradation due to water absorption and the generation of internal stress due to the progress of the curing reaction of the epoxy resin are the causes of the decrease in the strength of the epoxy resin.

中文翻译：

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户外曝晒对钢板粘接环氧树脂胶长期耐久性影响的评价

用于桥梁混凝土板加固的钢板粘结方法采用历史悠久，多年来一直发挥着重要作用。在定期检查中使用这种方法观察到有利条件；然而，作为耐久性测试的一部分，在标准环境条件下随着时间的推移暴露在室外后，环氧树脂粘合剂（其组成材料之一）的强度会降低。研究环氧树脂粘合剂强度降低的原因有助于提高未来基础设施维护的长期耐久性。包括暴露条件在内的环境因素的估计和进行加速试验的结果表明，环氧树脂粘合剂的性能受湿度的影响。此外，还观察到随着环氧树脂的反应进行而强度降低。这些结果表明，吸水引起的降解和环氧树脂固化反应进行引起的内应力的产生是环氧树脂强度下降的原因。