脱硝粉煤灰中氨对混凝土性能影响的研究进展

Research progress in the influence of ammonia in denitration fly ash on the concrete performances

脱硝粉煤灰作为矿物掺合料,会对混凝土产生诸多不良影响。通过对文献的研读,对脱硝粉煤灰中氨的存在形式、氨在水泥混凝土中的释放与留存及对混凝土性能影响等方面进行讨论分析,结果表明:脱硝粉煤灰中氨的存在形式为粉煤灰表面的NH 3物理吸附和残留在脱硝粉煤灰内的铵盐(NH 4 HSO 4、(NH 4)2 SO 4);脱硝粉煤灰对水泥混凝土性能的影响主要与铵含量有关,铵含量较高时会增加混凝土的用水量和含气量、延长凝结时间、降低强度;最后探讨了脱硝粉煤灰的使用措施,旨在为脱硝粉煤灰的资源利用化提供借鉴和参考。

Denitration fly ash is used as mineral admixture,which will have adverse effects on concrete.Through the study and analysis of the literature,the existence form of ammonia in denitrification fly ash,the release and retention of ammonia in cement concrete and the influence on concrete performance are discussed and analyzed.The results are showed that ammonia exists in the form of NH3 adsorbed on the fly ash surface and ammonium salts(NH 4 HSO 4,(NH 4)2 SO 4)remaining in the fly ash.The influence of denitration fly ash on the performance of cement concrete is mainly related to the content of ammonium.When the content of ammonium is higher,the water consumption and gas content of concrete will be increased,the setting time will be prolonged,and the strength will be reduced.Finally,the use measures of denitrification fly ash are discussed,aiming to provide reference for the utilization of denitration fly ash resources.