Effect of SiO2/Na2O mole ratio on the properties of foam geopolymers fabricated from circulating fluidized bed fly ash

• Published in: International journal of minerals, metallurgy and materials metallurgy and materials, 2014-06, Vol.21 (6), p.620-626
• Main Authors: Liu, Ze, Shao, Ning-ning, Huang, Tian-yong, Qin, Jun-feng, Wang, Dong-min, Yang, Yu
• Format: Article
• Language: English
• Subjects: Aluminosilicates; Aluminum silicates; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Compressive strength; Corrosion and Coatings; Fluidized beds; Fly ash; Geopolymers; Glass; Low temperature; Materials Science; Mechanical tests; Metallic Materials; Natural Materials; Silicon dioxide; Structural stability; Surfaces and Interfaces; Thin Films; Tribology; X-ray diffraction; X-ray spectroscopy; 二氧化硅; 地聚合物; 循环流化床; 性能; 摩尔比; 氧化钠; 泡沫; 粉煤灰
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-014-0950-5

Geopolymers are three-dimensional aluminosilicates formed in a short time at low temperature by geopolymerization. In this pa-per, alkali-activated foam geopolymers were fabricated from circulating fluidized bed fly ash （CFA）, and the effect of SiO2/Na2O mole ratio （0.91-1.68） on their properties was studied. Geopolymerization products were characterized by mechanical testing, scanning electron mi-croscopy （SEM）, energy-dispersive X-ray spectroscopy （EDX）, and X-ray diffraction （XRD）. The results show that SiO2/Na2O mole ratio plays an important role in the mechanical and morphological characteristics of geopolymers. Foam samples prepared in 28 d with a SiO2/Na2O mole ratio of 1.42 exhibit the greatest compressive strength of 2.52 MPa. Morphological analysis reveals that these foam geo-polymers appear the relatively optimized pore structure and distribution, which are beneficial to the structure stability. Moreover, a combina-tion of the Si/Al atomic ratio ranging between 1.47 and 1.94 with the Na/Al atomic ratio of about 1 produces the samples with high strength.