Abstract The exposure temperature significantly affects the diffusion of chloride ions in concrete, and, as such, it must be taken into consideration in the development of service-life prediction models for structures exposed to chloride-bearing environments. Most of the earlier studies have used cement paste to assess the effect of exposure temperature on chloride diffusion. In the reported study, chloride diffusion in Type I and fly ash (20% fly ash) cement concrete was evaluated under field and laboratory conditions. The laboratory concrete specimens were exposed to chloride solution maintained at four temperatures (22, 35, 50 and 60 °C) for 365 days. Beam specimens were exposed in the tidal zone of a marine exposure site, along the Arabian Gulf coast, for up to 10 years to study the chloride diffusion in the field specimens. The coefficient of chloride diffusion (Da) in the concrete specimens exposed to 22 or 35 ᵒC in the laboratory was less than that in the concrete specimens exposed to 50 and 60 ᵒC. The Da for Type I cement concrete specimens increased by 3.6 times as the temperature was increased from 22 to 60 ᵒC while this increase was 2.3 times for the fly ash cement concrete specimens for a similar increase in the temperature. The Da decreased with the period of exposure in the field specimens. The values of activation energy that can be used for predicting the chloride diffusion for exposure temperature within the range of 22–60 °C were developed based on the laboratory data. In addition, mathematical models were developed relating the coefficient of chloride diffusion in the field and laboratory concrete specimens. The developed models can be utilized to ascertain chloride diffusion in field specimens, utilizing the laboratory values, and hence calculate the useful service-life of structures.

中文翻译：

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暴露于现场和实验室条件的 I 型和粉煤灰水泥混凝土的氯化物扩散模型

摘要 暴露温度显着影响氯离子在混凝土中的扩散，因此在开发暴露于含氯环境的结构寿命预测模型时必须考虑到它。大多数早期研究都使用水泥浆来评估暴露温度对氯化物扩散的影响。在报告的研究中，在现场和实验室条件下评估了 I 型和粉煤灰（20% 粉煤灰）水泥混凝土中的氯化物扩散。实验室混凝土试样暴露于氯化物溶液中，保持在四个温度（22、35、50 和 60 °C）下 365 天。光束样本在阿拉伯湾沿岸的海洋暴露地点的潮汐带中暴露了长达 10 年，以研究野外样本中的氯化物扩散。实验室中暴露于 22 或 35 ᵒC 的混凝土试件的氯化物扩散系数 (Da) 小于暴露于 50 和 60 ᵒC 的混凝土试件。当温度从 22 升高到 60 ᵒC 时，I 型水泥混凝土试样的 Da 增加了 3.6 倍，而对于类似的温度升高，粉煤灰水泥混凝土试样的 Da 增加了 2.3 倍。Da随着野外样品暴露时间的延长而降低。可用于预测暴露温度在 22–60 °C 范围内的氯化物扩散的活化能值是根据实验室数据开发的。此外，还开发了与现场和实验室混凝土试件中氯离子扩散系数相关的数学模型。