碳酸钠、氢氧化钠与水玻璃复合激发对地聚物胶凝材料性能的影响

Effects of Sodium Carbonate,Sodium Hydroxide and Water Glass Composite Activation on Properties of Geopolymer Cementitious Materials

采用碳酸钠替代氢氧化钠调节水玻璃模数制备复合碱激发剂,研究不同碱掺量下碳酸钠掺入比例对地聚物胶凝材料净浆流动度、凝结时间及抗压强度的影响,并通过FT-IR、XRD和SEM试验分析地聚物胶凝材料水化产物的物相组成及微观形貌。结果表明,氢氧化钠与碳酸钠共同复合水玻璃的激发剂激发效果优于二者单独与水玻璃复合的激发剂,当碱掺量为6%(质量分数)、碳酸钠替代比例为40%(质量分数)时,地聚物胶凝材料净浆流动度为185 mm, 28 d抗压强度为94.4 MPa。碳酸钠替代比例增加可延长地聚物胶凝材料凝结时间,当替代比例为100%时,地聚物胶凝材料初凝时间、终凝时间可达372和420 min。不同碱组分激发剂作用时,地聚物胶凝材料水化产物相似,均以无定形铝硅酸盐C-(A)-S-H凝胶为主。

Composite alkali activator was prepared by using sodium carbonate instead of sodium hydroxide to adjust the modulus of water glass.The effects of different alkali content and sodium carbonate replacement ratio on fluidity,setting time,and compressive strength of geopolymer cementitious materials were studied.The phase composition and microstructure of hydration products of geopolymer cementitious materials were analyzed through FT-IR,XRD,and SEM experiments.The results show that the combined effects of sodium hydroxide and sodium carbonate combined with composite water glass activators are superior to the effects of their individual combined with water glass activators.When alkali content is 6%(mass fraction)and the replacement ratio of sodium carbonate is 40%(mass fraction),the fluidity of geopolymer cementitious materials reaches 185 mm,and 28 d compressive strength reaches 94.4 MPa.The increase of replacement ratio of sodium carbonate can prolong the setting time of geopolymer cementitious materials.When the replacement ratio reaches 100%,the initial setting time and final setting time of geopolymer cementitious materials reach 372 and 420 min.When different alkali components are used as activators,similar hydration products are observed in geopolymer cementitious materials,mainly consist of amorphous aluminosilicate C-(A)-S-H gel.