碱含量对粉煤灰基地质聚合物显微结构与性能的影响

Effect of Alkali Content on Microstructure and Properties of Fly Ash Based Geopolymers

以景德镇粉煤灰与炉渣为基础原料,通过添加激发剂压制成型,制备地质聚合物材料。主要研究了NaOH与KOH对粉煤灰基地质聚合物抗折强度的影响。在此基础上,对不同NaOH添加量样品进行了XRD、SEM及EDS表征。结果表明:NaOH添加量在0.5 wt.%~4.0 wt.%范围变化时,样品抗折强度变化规律符合二次拟合曲线Y=—2.344X^(2)+17.547X+5.512,在3.7 wt.%左右时,样品抗折强度有极大值,但有轻微泛碱现象。样品显微结构中出现Na型针沸石相与天然碱相,并随NaOH的增加,晶体形貌由无定形絮状变为纤丝状或聚束状。Na型针沸石Si/Al摩尔比先减小后增大,在NaOH添加量为3.0 wt.%时,其Si/Al摩尔比为1.31,为单链Si-O-Al结构的产物,抗折强度较大且不泛碱。

Fly ash based geopolymer materials were prepared by pressing Jingdezhen fly ash and slag at Jingdezhen as the main materials with the addition of alkaline agent.Effect of NaOH and KOH on bending strengths of the samples was studied.XRD,SEM and EDS were employed to characterize phase compositions and microstructure of the samples with different contents of NaOH.The bending strengths of the samples are consistent with the quadratic fitting curve Y=-2.344X^(2)+17.547X+5.512,when the NaOH content is vared in the range of 0.5 wt.~4.0 wt.%.The bending strength was maximized when the NaOH content was about 3.7 wt.%,but there was a slight efflorescence phenomenon.Ferrierite-Na and Trona were formed in the samples.The crystal morphology changed from amorphous flocculent to fibrous or bunched.The SiO_(2) and Al_(2)O_(3) molar ratio of Ferrierite-Na decreased first and then increases.When the content of NaOH is 3.0 wt.%,the SiO_(2)/Al_(2)O_(3) molar ratio is 1.31,thus forming a Si-O-Al single chain structure with enhanced bending strength.