摩尔比n（SiO2）/n（Al2O3）对发泡地质聚合物物理性能和微观结构的影响

Effect of n（SiO2）/n（Al2O3） molar ratio on physical properties and microstructure of foamed geopolymer

使用固硫灰(CFAS)、硅灰(SF)、水玻璃(WG)、NaOH和H2O2制备发泡地质聚合物,用硅灰来调节地质聚合物的摩尔比n(SiO2)/n(Al2O3),测试新拌浆体的发泡倍数、发泡速率。对硬化后浆体进行强度和表观密度等性能的测试,结合Image-Pro Plus软件分析孔径分布;通过X射线衍射(XRD)、傅里叶红外光谱(FTIR)、扫描电镜(SEM)等手段分析发泡地质聚合物的微观结构。结果表明:在试验条件下,摩尔比n(SiO2)/n(Al2O3)的提高加速了水化反应速率,适宜的摩尔比使得发泡时间提前;红外光谱波数的迁移表明,碱激发后Si—O与Al—O键发生重排,合适的摩尔比对地质聚合物的重排反应是有利的,提高了聚合度;XRD图谱显示有沸石等产物生成;当摩尔比n(SiO2)/n(Al2O3)为2.79时,试件28 d强度及表观密度分别为1.06 MPa和231 g/L,此时试件微观结构具有良好的致密性。

The foaming geopolymer was prepared by experiments using circulating fluidized bed combustion fly ash(CFAS),silica fume(SF),water glass(WG),NaOH and H2O2,and silica fume was used to adjust the n(SiO2)/n(Al2O3)molar ratio of the geopolymers,the fresh paste was tested for foaming expansion factor and foaming rate.The strength and apparent density of the paste were tested after hardening.This paper analyzed the pore size distribution by Image-Pro Plus software,and the microstructures of the foamed geopolymers were analyzed by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR)and scanning electron microscope(SEM).The results show that the increase of the molar ratio of n(SiO2)/n(Al2O3)accelerates the hydration reaction rate,and the appropriate ratio makes the foaming time advance.The wavelength shift in the FTIR indicates that the Si—O and Al—O bonds rearrange after alkali-excited,and the appropriate ratio is favorable for the rearrangement reaction of the geopolymer and increases the degree of polymerization.The product such as zeolite was formed found by XRD pattens.When the n(SiO2)/n(Al2O3)molar ratio is 2.79,the strength and apparent density of the specimen in 28 d are 1.06 MPa and 231 g/L,and the microstructure of the specimen has good compactness.