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通过人工气候模拟潮差区氯离子环境下混凝土的暴露试验,测定了不同暴露时间后的混凝土自由氯离子浓度,分析了其扩散系数及其时变性;以MIP法测定了不同暴露时间下混凝土的总孔隙率和孔径分布等孔隙特征参数,分析了其时变性;研究了潮差环境下混凝土扩散系数与孔隙微观参数的时变性关系,混凝土孔表面分形维数与扩散系数的关系。结果表明:在模拟潮差环境下,随着暴露时间的延长,混凝土氯离子扩散系数和总孔隙率均逐渐减小,而孔表面分形维数逐渐增大;不同暴露时间后,混凝土氯离子扩散系数与其各级孔隙率有较好的相关关系;混凝土不同孔径范围的孔表面分形维数与其氯离子扩散系数之间的相关性不同,其中以孔径范围为100~1000 nm的大毛细孔的孔表面分形维数相关性最高。
The free chlorine concentration of concrete after different exposure time was measured and the diffusion coefficient and its time-varying property were analyzed by artificial climate simulation test of concrete exposed to chloride ions in tidal range. The MIP method was used to measure the concrete Total porosity and pore size distribution, and then analyze their time-varying characteristics. The relationship between the time-variation of concrete diffusion coefficient and pore microscopic parameters under tidal range and the relationship between the fractal dimension of surface of concrete and the diffusion coefficient are studied. The results show that under the condition of simulated tidal range, the chloride ion diffusion coefficient and total porosity of concrete decrease gradually with the increase of exposure time, while the fractal dimension of pore surface increases gradually. After different exposure time, the chloride ion diffusion There is a good correlation between the coefficient and porosity at all levels. The correlation between the fractal dimension of the pore surface and the chloride ion diffusion coefficient in different pore size ranges is different. Among them, pores with large pores with a pore size in the range of 100-1000 nm The fractal dimension of the surface has the highest correlation.