Preparation and microstructure characterization of poly-sialate-disiloxo type of geopolymeric cement

Abstract

In order to investigate the influence of three key molar ratios (n(SiO₂)/n(Al₂O₃), n(K₂O)/n(Al₂O₃) and n(H₂O)/n(K₂O)), a total of nine potassium poly-sialate-disiloxo (K-PSDS) geopolymeric cement matrices were designed according to orthogonal design principle. Subsequently, XRD, ESEM-EDXA and MAS-NMR techniques were employed to further characterize the microstructure of the most fully reacted geopolymeric cement matrix. The experimental results show that n(K₂O)/n(Al₂O₃) has the most significant effect on compressive strength amongst the three ratios. The highest compressive strength (20.1 MPa) can be achieved when n(SiO₂)/n(Al₂O₃)=6.5, n(K₂O)/n(Al₂O₃)=0.8 and n(H₂O)/n(K₂O)=10.0. The FTIR spectra of nine PSDS geopolymeric cement matrices also indicate that geopolymeric cement matrix with the highest strength is the most fully reacted one and possesses the largest amount of geopolymeric cement products. The microscopic analysis reveals that PSDS geopolymeric cement matrix possesses structural characteristics similar to gel substances in having a wide range of Si endowments, but predominantly the framework molecular chains of Si partially replaced by 4-coordinated Al tetrahedral.

Keywords

geopolymeric cement / poly-sialate-disiloxo / preparation / microstructure

References

[1] DavidovitsJ.. Geopolymers and geopolymeric new materials[J]. Journal of Thermal Analysis, 1989, 35(2): 429-441

[2] DavidovitsJ.. Geopolymer chemistry and properties[C]. Proceedings of the First European Conference on Soft Mineralog, 1988, Compiegne, The Geopolymer Institute: 25-48

[3] DuxsonP., FenandezJ. A., ProvisJ. L., LukeyG. C., PalomoA., van DeventerJ. S. J.. Geopolymer technology: The current state of the art[J]. Journal of Materials Science: Special Section, 2007, 42(9): 2917-2933

[4] RanganV.. Advances in geopolymer concrete[J]. Engineers Australia, 2003, 75(1): 7-10

[5] DavidovitsJ., DouglasC. C., JohnH. P., DouglasJ. R.. Geopolymeric concretes for environmental protection[J]. Concrete International: Design & Construction, 1990, 12(7): 30-40

[6] DuxsonP., ProvisJ. L., LukeyG. C., van DeventerJ. S. J.. The role of inorganic polymer technology in the development of green concrete[J]. Cement and Concrete Research, 2007, 37(12): 1590-1597

[7] NowakR.. Geopolymer concrete opens to reduce CO₂ emissions[J]. The New Scientist, 2008, 197(2640): 28-29

[8] ZhangY.-s., SunWei.. Fly ash based geopolymer concrete[J]. Indian Concrete Journal, 2006, 80(1): 20-24

[9] HonglingW., HaihongL., FengyuanY.. Synthesis and mechanical properties of metakaolinite-based geopolymer[J]. Colloid Surface A, 2005, 268(1/3): 1-6

[10] SofiM., van DeventerJ. S. J., MendisP. A., LukeyG. C.. Engineering properties of inorganic polymer concretes (IPCs)[J]. Cement and Concrete Research, 2007, 37(2): 251-257

[11] DaeikK., LaiH. T., ChilingarG., TenF. Y.. Geopolymer formation and its unique properties[J]. Environmental Geology, 2006, 51(1): 103-111

[12] van JaarsveldJ. G. S., van DeventerJ. S. J.. The potential use of geopolymeric materials to immobilize toxic metals: Part I. Theory and applications[J]. Mineral Engineering, 1997, 10(7): 659-669

[13] BakharevT.. Resistance of geopolymer materials to acid attack[J]. Cement and Concrete Research, 2005, 35(4): 658-670

[14] LyonR. E., FodenA., BalaguruP. N., FodenA. J., SorathiaU., DavidovitsJ.. Fire-resistant aluminosilicate composites[J]. Journal of Fire and Materials, 1997, 21(2): 67-73

[15] BakharevT.. Durability of geopolymer materials in sodium and magnesium sulfate solutions[J]. Cement and Concrete Research, 2005, 35(6): 1233-1246

[16] DavidovitsJ.. High alkali cements for 21st century concretes[C]. Concrete Technology, Past, Present, and Future, 1994, Detroit, American Concrete Institute: 383-397

[17] ZuhuaZ., MaoY., HuajunZ., YueC.. Role of water in the synthesis of calcined kaolin-based geopolymer[J]. Applied Clay Science, 2009, 43(2): 218-223

[18] DuxsonP., ProvisJ. L.. Designing precursors for geopolymer cements[J]. Journal of the American Society, 2009, 91(12): 3864-3869

[19] ZhangY. S., SunW.. Study on polycondensation process of metakaolin based geopolymeric cement using semi-empirical AM1 calculations[J]. Advances in Cement Research, 2008, 21(2): 67-73

[20] ZhangY. S., SunW., LiZ. J.. Geopolymer extruded composites with incorporated fly ash and polyvinyl alcohol short fiber[J]. ACI Materials Journal, 2009, 106(1): 3-10

[21] de SilvaP., Sagoe-CrenstilK.. Medium-term phase stability of Na₂O-Al₂O₃-SiO₂-H₂O geopolymer systems[J]. Cement and Concrete Research, 2008, 38(6): 870-876

[22] DombrowskiK., WeilM., BuchwaldA.. Geopolymer binders[J]. ZKG International, 2008, 61(3): 70-80

[23] KrivenW., BellJ. L., GordonM.. Microstructure and microchemistry of fully-reacted geopolymers and geopolymer matrix composites[J]. Ceramic Transactions, 2004, 153: 227-250

[24] SchmuckerM.. Microstructure of sodium polysialate siloxo geopolymer[J]. Ceramics International, 2005, 31(3): 433-437

[25] Davidovits J. Chemistry of geopolymeric systems terminology[C]//Proceedings of Geopolymere’ 99 Institute Geopolymer. Saint-Quentin, 1999: 9–44.

[26] ValeriaF. F. B., KenenethJ. D. M., ClelioT.. Synthesis and characterization of materials based on inorganic polymers of alumina and silica: Sodium polysialate polymers[J]. International Journal of Inorganic Materials, 2000, 2(4): 309-317

[27] AkolekarD., ChaffeeA., RussellF. H.. The transformation of kaolin to low-silica X zeolite[J]. Zeolites, 1997, 19(5): 356-365

[28] van JaarsveldJ. G. S., van DeventerJ. S. J., SchwartzmanA.. The potential use of geopolymeric materials to immobilize toxic metals: Part II. Material and Leaching Characteristics[J]. Minerals Engineering, 1999, 12(1): 75-91

[29] EngelhardtG., FahlkeB., MngiM., LippmaaE.. High resolution ²⁹Si NMR of dealuminated Y-zeolites. 2. Silicon, aluminium ordering in the tetrahedral zeolite lattice[J]. Zeolites, 1983, 3(3): 239-243

[30] WangP., PanZ.-l., WengL.-bao.Mineralogy[M], 1984, Beijing, China Geological Press

[31] DuxsonP., ProvisJ. L., LukeyG. C., SeparovicF., van DeventerJ. S. J.. ²⁹Si NMR study of structural ordering in aluminosilicate geopolymer gels[J]. Langmuir, 2005, 21(7): 3028-3036

[32] DavidovitsJ.. Geopolymers: Man-made rock geosynthesis and resulting development of very early high strength cement[J]. J Materials Education, 1994, 16(2/3): 91-139

[33] EngelhardtG., MichelD.High-resolution solid-state NMR of silicates and zeolites[M], 1987, New York, Wiley