关于亚甲蓝法表征机制砂中黏土含量的思考

Thoughts on characterization of clay content in manufactured sand by methylene blue method

机制砂在生产过程中带入的一定含量膨胀性黏土矿物不仅对外加剂和水具有显著的吸附作用,还会对混凝土性能产生不良影响,其影响程度因黏土类型与含量的不同而存在明显差异。目前国内外标准大多采用亚甲蓝法来表征机制砂中黏土含量,系统分析了亚甲蓝法的测试原理和国内外亚甲蓝法的差异,归纳了影响机制砂亚甲蓝值的关键因素,分析了机制砂亚甲蓝值、含泥量与混凝土性能三者间相关性,最后指出了现行亚甲蓝法存在的问题并提出相关建议。

In the production process of manufactured sand,a certain content of expansive clay minerals will be brought in,which not only has significant adsorption to additives and water,but also has adverse effects on the performance of concrete.The degree of influence is obviously different due to different clay types and contents.At present,most domestic and foreign standards use methylene blue method to characterize the clay content in manufactured sand.The test principle and the differences of methylene blue method at home and abroad are systematically introduced,the key factors affecting the methylene blue value of manufactured sand are summarized,and the correlation among the methylene blue value of manufactured sand,mud content and concrete performance are analyzed.Finally,some problems in the current methylene blue method are pointed out and relevant suggestions are put forward.