碳化与硫酸盐溶液干湿循环后混凝土断裂韧度

Fracture toughness of concrete after carbonation and wet-dry cycle of sulfate solution

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 this paper, the effects of deteriorations is studied, such as carbonation and wet-dry cyclein sulfate solution, upon fracture toughness of concrete. Through the three-point bending test on thenotched beams of concrete after carbonation and wet-dry cycle in sulfate solution, the effects of carbon-ation time（t） and wet-dry cycle number（n） upon the fracture toughness of concrete were studied. The re-sults show that carbonation and wet-dry cycle deteriorate the fracture toughness to some extent. Degradationfactor（R） is less than 1. Fracture toughness decreases as t（or n） increases. R significantly decreases as（orn） increases,and statistical analysis indicates that t and n meet the relation of exponential function with R respectively. Because of the obvious interaction between carbonation and wet-dry cycle, the individual ef-fect of carbonation（or wet-dry cycle） is more serious than the alternate one. Based on the test results,the calculation model is established for calculating fracture toughness of concrete deterioration. This modelis helpful to analyze the crack propagation and fracture toughness of concrete deterioration.