脱硝粉煤灰铵含量对水泥胶砂性能影响研究

研究了脱硝粉煤灰的铵含量对水泥胶砂物理性能的影响规律,提出脱硝粉煤灰残留铵的安全含量阈值。结果表明:随着粉煤灰中铵含量的逐渐升高,水泥标准稠度用水量、需水量比和含气量呈现逐渐升高的趋势,而胶砂强度、活性指数和流动度逐渐降低,且凝结时间显著延长。粉煤灰铵含量对水泥安定性、水化热、假凝和干缩性能的影响并不明显。在一般工程情况下,建议脱硝粉煤灰的铵含量应不大于200 mg/kg。

Effect of ammonium content in denitrification fly ash on properties of cement mortar

In this paper the effect of ammonium content in denitrification fly ash on physical properties of cement mortar were studied and the security content threshold value of residual ammonium in denitrification fly ash was proposed. The results show that with the increasing of ammonium content in fly ash, the water requirement for normal consistency of cement, water demand ratio and air content of cement presenting the gradual upward trend, the cement mortar strength, activity index and fluidity of cement were gradually reduced, moreover, the setting time of cement was prolonged. The ammonium content in fly ash has little effect on cement soundness, hydration heat, false set and dry shrinkage capability. In general engineering conditions, it was recommended that the ammonium content in denitrification fly ash should be no higher than 200 mg/kg.