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为研究劣化作用对混凝土断裂韧度的影响,通过碳化、硫酸盐溶液干湿循环单一及交替作用后混凝土切口梁三点弯曲试验,探讨了碳化时间、硫酸盐溶液干湿循环次数对混凝土断裂韧度的影响。结果表明:碳化和硫酸盐溶液干湿循环均会对混凝土断裂韧度造成一定程度的劣化,劣化程度因子小于1。随着碳化时间和硫酸盐溶液干湿循环次数的增加,断裂韧度呈减小趋势;单一劣化作用时,随着碳化时间和硫酸盐溶液干湿循环次数的增加,劣化程度因子减小显著,且碳化时间、硫酸盐溶液干湿循环次数与劣化程度因子之间分别满足近似指数关系;由于碳化和硫酸盐溶液干湿循环的交互影响,单一劣化作用对断裂韧度的劣化程度逐渐呈现大于交替劣化作用影响的趋势。在分析试验结果的基础上,建立了劣化作用后混凝土断裂韧度计算模式,该模式有助于分析劣化作用后混凝土裂缝扩展并预测其断裂韧度。
In order to study the effect of deteriorating effect on the fracture toughness of concrete, three-point bending test of concrete notched beam after carbonization and sulfate solution wet-dry cycles was conducted. The effects of carbonation time and wet-dry cycle times of sulfate solution on concrete fracture toughness Degree of influence. The results show that both the wetting and drying cycles of carbonation and sulphate solution will cause a certain degree of deterioration of the fracture toughness of the concrete with the degree of deterioration less than 1. The fracture toughness decreases with the increase of carbonization time and the number of cycles of sulphate drying and wetting. At the time of single degradation, the degree of deterioration decreases significantly with the increase of carbonation time and the number of wetting and drying cycles of sulphate solution. And the carbonation time, the number of cycles of desiccation and desiccation of sulfate solution respectively satisfy the approximate exponential relationship; due to the interaction between carbonation and the wet-dry cycle of the sulfate solution, the degree of deterioration of fracture toughness by single degradation is gradually greater than the alternation Deterioration effect of the trend. Based on the analysis of experimental results, the calculation mode of the fracture toughness of concrete after degradation is established, which can help to analyze the crack growth and predict the fracture toughness of concrete after the deterioration.