矿物超细粉混合骨料混凝土微观结构研究

Study on Microstructure of Mixed Aggregate Concrete with Mineral Admixtures

利用扫描电镜(SEM)观察冻融试验前后单掺粉煤灰和复掺粉煤灰、硅粉时混合骨料混凝土的骨料-水泥石界面过渡区(ITZ)的微观结构和水化产物,从微观层面分析矿物超细粉对混合骨料混凝土抗冻性能的影响。SEM分析结果表明:单掺30%粉煤灰比复掺20%粉煤灰与10%硅粉的界面结构劣化严重,并且粉煤灰与硅粉复掺和未掺掺合料的混凝土界面结构与抗冻性能较为接近。因此采用20%粉煤灰与10%硅粉复掺来替代部分水泥可以保证混凝土具有较好抗冻性能。

For mixed aggregate concrete which single mixing with fly ash or double mixing with fly ash and silica fume, before and after freeze-thaw test observe microstructure and hydrate of aggregate-cement in interfacial transition zone （ITZ）under scanning electron microscope （SEM）. Research the influence of different mineral admixture to the frost resistance of mixed aggregate concrete from the micro level. SEM analysis indicate that ： the degradation degree of interfacial structure for single mixing with 30% fly ash is more serious than that for double mixing with 20% fly ash and 10% silica fume. In addition, concrete mixing with fly ash and silica fume has the similar interracial structure and frost resistance with concrete that has no mineral admixtures. Therefore double mixing with 20% fly ash and 10% silica fume can replaces a part of cement and ensure the concrete has good frost resistance properties.