A Prediction Model of Semi-Carbonated Zone Length of Concrete Under Natural Exposure Environment
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摘要: 对西安地区某钢筋混凝土工业厂房进行了现场测试和试验研究,采用压榨法逐层测试了混凝土圆柱体试样孔溶液pH值,根据测试结果确定了混凝土部分碳化区长度。同时根据碳化过程中的物质平衡,采用数值方法计算了混凝土碳化进程中物质含量的变化,得到了混凝土部分碳化区长度数值模型。将部分碳化区长度数值计算结果与试验结果进行了对比,验证了数值模型的准确性。分析结果表明:混凝土部分碳化区长度随着水灰比的增大而增加;随水泥用量和相对湿度的增加而减小;相对湿度对部分碳化区长度的影响最为显著,当环境湿度RH≥80%后,部分碳化区基本消失;当RH=70%时,部分碳化区长度较短,基本可以忽略;CO2浓度和碳化时间对混凝土部分碳化区长度影响较小。Abstract: The paper presented the results of the in-situ test and experimental study on a reinforced concrete industrial plant in Xi'an. The pH values of the pore solution in the cylinder samples were measured layer-by-layer by expression method. The length of semi-carbonated zone was determined according to the test results. The mass balance in the carbonation process was analyzed and the change of substance content in the carbonation process was calculated by numerical method, and the numerical model of semi-carbonated zone length of concrete was obtained. The accuracy of the numerical model was valid by comparing the numerical analysis results with the experimental results. The results showed that the semi-carbonated zone length increased with the increase of water-cement ratio, while decreasing with the increase of cement content and relative humidity. Relative humidity had the most significant effect on the semi-carbonated zone length. When RH ≥ 80%, the semi-carbonated zone disappearred. The semi-carbonated zone length was relatively short at RH = 70%, which could be ignored. The CO2 concentration and carbonation time had little effect on the semi-carbonated zone length.
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Key words:
- natural exposure /
- expression method /
- pH /
- semi-carbonated zone
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