矿物掺合料对混合骨料混凝土微观结构的影响

Effect of mineral admixtures on microstructure of mixed aggregate concrete

利用扫描电镜(SEM)观察浮石替代率为30%的混合骨料混凝土冻融试验前后在单掺粉煤灰以及复掺粉煤灰及硅粉时骨料-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掺合料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,采用以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的抗冻性能。

For mixed aggregate concrete which replacement rate of pumice is 30％,under scanning electron microscope（SEM）,observe microstructure and hydrate of aggregate-cement in interfacial transition zone （ITZ）,which single mixed with fly ash and double mixed with fly ash and silica fume before and after freeze-thaw test.Analyze the influence of different mineral admixture about the frost resistance of mixed aggregate concrete from the micro level.SEM analysis shows that the degradation degree of interfacial structure for single 30％ fly ash is more serious than that for double mixing 20％ fly ash and 10％ silica fume.In addition,double mixing fly ash and silica fume concrete has the similar interfacial structure and frost resistance with single mixing fly ash concrete.Therefore replacing a part of cement with double mixing 20％ fly ash and 10％ silica fume can ensure the concrete has good frost resistance properties.