聚合硫酸铝改性低碱度水泥性能研究

以水泥、硅灰和粉煤灰为主要胶凝材料制备的低碱度水泥可应用于放射性焚烧灰的固化,但其存在早期强度发展慢、后期强度不高的问题。本文以聚合硫酸铝作为添加剂激发火山灰材料反应活性,通过测定不同掺量聚合硫酸铝加入后固化体的抗压强度、孔隙率及pH值变化,并结合水化产物组成与含量、水化放热特性等表征手段,分析了聚合硫酸铝对低碱度水泥早期水化过程的影响规律和作用机理。结果表明:掺入聚合硫酸铝可以显著提高低碱度水泥固化体的早期抗压强度,使水化放热峰提前,促进了火山灰反应的发生,提高了水化产物的生成量,使微观结构更加密实,同时有效降低试样的早期碱度,有利于抑制焚烧灰中活性铝的腐蚀反应。

Properties of Polyaluminum Sulfate-Modified Low-Alkalinity Cement

The compressive strength at early and late age is relatively low for low-alkalinity cement prepared by ordinary Portland cement, silica fume and fly ash for the solidification of radioactive incineration ash. In this study, polyaluminum sulfate was used as additive to stimulate the reactivity of pozzolanic materials in the low-alkalinity cement. The effect and mechanism of polyaluminum sulfate on the early age hydration of low-alkalinity cement were characterized by evaluating the compressive strength, porosity, pH value, phase assemblage and microstructure of low-alkalinity cement after addition of polyaluminum sulfate. The results indicate that the incorporation of polyaluminum sulfate significantly improves the early age compressive strength of the low-alkalinity cement. The exothermic peak of early age hydration is advanced and the pozzolanic reaction is promoted. The amount of hydration products increases, and the microstructure is densified. The early age alkalinity effectively reduces, which is beneficial to inhibit the corrosion reaction of metal aluminum in the incineration ash waste form.