直流电预养护对NaOH激发粉煤灰早期强度的影响研究

Effect of Direct Current Pre-curing on Early Age Strength of Fly Ash Activated by NaOH

以超细粉煤灰为原料,NaOH为激发剂,在常温养护前用短时间(1 h)直流电预养护方式有效改善了碱激发粉煤灰胶凝材料的早期性能。研究了直流电预养护对碱激发粉煤灰胶凝材料净浆试样内部温度、凝结时间以及力学性能的影响。结果表明:常温养护前使用短时间(1 h)直流电预养护可以显著改善材料的凝结性能和早期力学性能。在直流电预养护条件下,养护电压越高,碱激发胶凝材料试样内部温度的峰值也越高。在常温养护条件下,碱激发粉煤灰主要发生的是粉煤灰中的部分玻璃相溶解缩聚生成少量无定形铝硅酸盐凝胶的水化反应,而使用直流电预养护后可使碱激发胶凝材料在早期水化过程中生成更多的铝硅酸盐凝胶和羟基方钠石,从而改善了材料的早期力学性能。

Using ultra-fine fly ash as raw materials and NaOH as activator,the early properties of alkali-activated fly ash cementitious material were improved effectively by short-time(1 h)direct current pre-curing method before the normal temperature curing.The effects of direct current pre-curing on the internal temperature,setting time and mechanical properties of alkali-activated fly ash cementitious materials were studied.The results show that the early mechanical performance of alkali-activated fly ash cementitious materials can be significantly improved by use of short-time(1 h)direct current pre-curing before the normal temperature curing.The higher the curing voltage,the higher the maximum temperature of the AAFA cementitious material under electric curing.Under the room temperature curing,the main occurrence of alkali-activated fly ash is the hydration reaction that partial glassy phase in fly ash is dissolved and polymerized to form a small amount of amorphous aluminosilicate gels.More aluminosilicate gels and hydroxysodalite are formed in the early hydration process of alkali-activated cementitious material by using direct current pre-curing,thus the early age mechanical performance of the materials are improved.