粉煤灰中残留氨含量对混凝土性能影响

Effect of Residual Ammonia Content in Fly Ash on Concrete Performance

分析了粉煤灰中残留氨的存在形态,初步确定残留氨的存在形态为物理吸附的氨气、硫酸铵和硫酸氢铵。通过外掺硫酸铵的方法,研究粉煤灰中残留氨含量对混凝土性能的影响,研究结果表明:当粉煤灰中硫酸铵含量在2 000 mg/kg范围内,粉煤灰掺量为35%时,随着硫酸铵含量的增加,混凝土初始含气量略微增大,抗冻性能和抗渗性能略微降低,混凝土的初始坍落度和1 h变化率、1 h含气量变化率、凝结时间、抗压强度和劈拉强度不受硫酸铵含量变化的影响。

The existing form of residual ammonia in fly ash is analyzed and initially determined as ammonia, ammonium sulfate and ammonium hydrogen sulfate. The effects of residual ammonia content in fly ash on concrete performance are studied by the method of ammonium sulfate addition. The research results show that, when the content of ammonium sulfate in fly ash is not more than 2 000 mg/kg and the dosage of fly ash is 35%, the initial gas content of concrete increases slightly and the frost resistance and impermeability decrease slightly with the increases of ammonium sulfate content, and the initial slump, 1h change rate of slump, 1h gas content change rate, setting time, compressive strength and tensile strength are not affected by the change of ammonium sulfate content.