脱硝粉煤灰对水泥混凝土性能影响

Effect and Mechanism of Denitrification Fly Ash on Performance of Cement Concrete

现有的脱硝技术导致燃煤电厂脱硝后的粉煤灰中含有氨氮物质。为了更好地解决脱硝粉煤灰应用出现的问题,研究脱硝粉煤灰对水泥混凝土性能的影响则至关重要与紧迫。通过对文献分析总结,脱硝粉煤灰的氨氮物质以NH 4 HSO 4或(NH 4)2 SO 4为主要存在形式,或有吸附在粉煤灰上的NH 3。脱硝粉煤灰作为掺合料,其氨氮物质主要以NH 3的形式释放且集中在搅拌后前8h,约有20%~70%留存在混凝土体系中,脱硝粉煤灰使水泥凝结时间延长,有一定的减水作用,提高流动度,但强度有所降低。

After the denitration of coal-fired power plants,the denitration technology leads to denitrification fly ash contain ammonia nitrogen.In order to solve the problems in the application of denitrified fly ash,the paper study the effect of denitrification fly ash on the performance of cement concrete.By analyzing and summarizing the literature,it is proposed that the ammonia nitrogen material of denitrification fly ash mainly exists in the form of NH 4HSO 4 or(NH 4)2SO 4,or there is NH 3 adsorbed on fly ash.Denitrification fly ash is used as an admixture.The ammonia nitrogen is mainly released as NH 3 and concentrated in the first 8 hours after stirring.About 20%~70%of it is left in the concrete system.The denitrification fly ash prolongs the cement setting time.The water-reducing effect improves the mobility,but the strength is reduced.