Liu Yinglong, Lin Pengzhen, He Zhigang, Ma Junjun
Key Laboratory of Road & Bridge and Underground Engineering of Gansu Province, Lanzhou Jiaotong University, Lanzhou 730070, China.
Materials (Basel). 2022 Apr 7;15(8):2711. doi: 10.3390/ma15082711.
In order to quantitatively analyze the factors affecting the carbonation of reinforced concrete structures, the carbonation coefficient model is established based on 1834 groups of test data from natural carbonation and indoor accelerated tests in this paper. The main factors considered in the statistical model are the environmental temperature, the concentration of carbon dioxide, relative humidity, water-cement ratio, fly ash replacement, compressive strength of 28 days, curing time, compaction type, exposure to a salt environment, and environmental exposure classes. Based on the multiple nonlinear regression method, the carbonation coefficient model is fitted in two sections according to the different environmental exposures of the concrete structure. To analyze the applicability of the formula, the statistical formulas of relative humidity less than 70% and relative humidity higher than 70% are verified by the test data, and satisfactory results are obtained. Based on the quantitative analysis of the statistical model, the specific effects of relative humidity, strength, carbon dioxide content, fly ash, and curing time on concrete carbonation are clarified. The results show that the factors affecting carbonation are also different with different humidity values in the exposed environment of the concrete structure. When the relative humidity of the exposed environment is less than 70%, the parameters that have a great impact on concrete carbonation are fly ash replacement, compressive strength of 28 days, relative humidity, and the concentration of carbon dioxide. Among them, fly ash replacement, relative humidity, and the concentration of carbon dioxide can promote the carbonation of concrete. When the relative humidity of the exposed environment is higher than 70%, the parameters that have a great impact on concrete carbonation are the concentration of carbon dioxide, relative humidity, compressive strength of 28 days, curing time, and exposure classes. Only the concentration of carbon dioxide is conducive to the carbonation of concrete, and relative humidity has a very significant effect on concrete carbonation.
为定量分析影响钢筋混凝土结构碳化的因素，本文基于1834组自然碳化和室内加速试验的测试数据建立了碳化系数模型。统计模型中考虑的主要因素有环境温度、二氧化碳浓度、相对湿度、水灰比、粉煤灰取代率、28天抗压强度、养护时间、压实类型、盐环境暴露情况以及环境暴露等级。基于多元非线性回归方法，根据混凝土结构不同的环境暴露情况分两段拟合碳化系数模型。为分析公式的适用性，通过试验数据对相对湿度小于70%和相对湿度大于70%的统计公式进行了验证，取得了满意的结果。基于统计模型的定量分析，明确了相对湿度、强度、二氧化碳含量、粉煤灰和养护时间对混凝土碳化的具体影响。结果表明，在混凝土结构暴露环境中，不同湿度值下影响碳化的因素也不同。当暴露环境的相对湿度小于70%时，对混凝土碳化影响较大的参数有粉煤灰取代率、28天抗压强度、相对湿度和二氧化碳浓度。其中，粉煤灰取代率、相对湿度和二氧化碳浓度会促进混凝土碳化。当暴露环境的相对湿度大于70%时，对混凝土碳化影响较大的参数有二氧化碳浓度、相对湿度、28天抗压强度、养护时间和暴露等级。只有二氧化碳浓度有利于混凝土碳化，相对湿度对混凝土碳化有非常显著的影响。
