粉煤灰对混凝土AAR有效碱的影响及机理

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粉煤灰对混凝土AAR有效碱的影响及机理

发布时间: 2012-09-15 11:27 查看: 2270次

混凝土碱集料反应有效碱粉煤灰混凝土孔溶液
摘要：

为准确从碱与活性集料反应的角度掌握碱集料反应(AAR),在前人研究基础上,赋予有效碱更进一步的定义,将进入活性集料中的碱称为有效碱.采用火焰光度法对有效碱含量和混凝土孔隙溶液碱离子浓度进行了测定,并据此分析了粉煤灰抑制AAR机理.试验结果表明:掺加粉煤灰后,混凝土基体孔隙溶液碱离子浓度降低,从而减少了活性集料中的有效碱,而粉煤灰掺入改变基体扩散系数对有效碱的影响则是次要的.因此可通过测量早期孔隙溶液碱离子浓度变化来评价粉煤灰对AAR的抑制效果.

Abstract：

A further definition of effective alkali is proposed based on the studies of predecessors and the alkali entering aggregates is called effective alkali,which is adopted to grasp alkali aggregates reaction (AAR) accurately from the reaction angle of alkali and reactive aggregates.The effective alkali content and alkali ions concentration of concrete pore solution were investigated by flame photometry and accordingly the inhibitory mechanism of fly ash on AAR was analyzed.The results show that after the addition of fly ash the alkali ions concentration of concrete pore solution decreases,which reduces the effective alkali in reactive aggregates,while the influence of paste diffusion coefficient change for alkali ions on the effective alkali is secondary.Therefore,the inhibitory effect of fly ash on AAR can be evaluated by measuring the early alkali ions concentration change of concrete pore solution.

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