硅酸钠和硅灰激发剂对地质聚合物混凝土性能的影响

Influence of Sodium Silicate and Silica Fume Activator on the Properties of Geopolymer Concrete

地质聚合物中常用的硅酸钠和氢氧化钠复合碱性激发剂存在在碱性条件下易发生自聚合从而导致地质聚合物混凝土工作性能下降的问题。本工作研究了硅酸钠激发剂与硅灰活化液激发剂对地质聚合物混凝土性能的影响,通过Pearson相关系数分析了两种激发剂对不同配合比地质聚合物塌落度的影响程度。分析表明,与硅酸钠复合碱性激发剂相比,硅灰活化液激发下地质聚合物的塌落度受矿粉、煅烧菱镁矿等影响更小,矿粉的影响系数绝对值由0.785降至0.409,煅烧菱镁矿的影响系数绝对值由0.829降至0.156,矿粉、煅烧菱镁矿与塌落度相关性由显著变为不显著,因此硅灰激发下地质聚合物的工作性能更加稳定。当地质聚合物混凝土抗压强度较高时,相比硅酸钠复合碱性激发下的地质聚合物,硅灰液激发下的地质聚合物试块表面的裂缝和内部孔隙状况更好。优化配合比后,在20℃、湿度大于95%的条件下,地质聚合物混凝土7 d抗压强度达到了43.36 MPa,有较高的早期强度。

Sodium silicate and sodium hydroxide(NaOH)are commonly used as activator to make geological polymer composite.It will cause the decline of the performance of geopolymer concrete when it is prone to polymerization in the surrounding of alkaline.The influence of the performance of geopolymers was researched with sodium silicatecompound alkaline activator and silica fume activator.The influence of two kinds of activators on the slump of geopolymers with different mix ratios was analyzed by Pearson correlation coefficient.The analysis showed that the slump of geopolymers with silica fume activator was less affected by mineral powder and Calcined magnesite than that of sodium silicate activator.The relative coefficient of mineral powder is decreased from 0.785 to 0.409.The absolute relative coefficient of calcined magnesite is decreased from 0.829 to 0.156.The correlation between slag,calcined magnesite and slump changed from significant to insignificant.Geopolymer concrete had more stable performance with silica fume activator.The geopolymer concrete excited by silica fume activator compared with the sodium silicate composite alkaline activator,the cracks and internal pores on the surface of the specimens are less when the compressive strength is higher.The compressive strength of geopolymer concrete excited by silica fume activator reached 43.36 MPa with the condition of 20℃and more than 95%humidity.It shows good early strength.