Abstract
The influences of concentration and modulus of sodium silicate solution and curing mode on the phase composition, microstructure and strength development in the geopolymers prepared using Class F fly ash were investigated. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and MAS NMR were utilized. Results show that the compressive strength increases as sodium silicate solution modulus increases, but when modulus exceeds 1.4, the compressive strength decreases, and it decreases markedly while the modulus is greater than 2.0. The compressive strength was improved by the increase of sodium silicate solution concentration. When the concentration is 32%, the compressive strength reaches the maximum, then it reduces as concentration increasing. Elevated temperature can increase the strength of samples that synthesized from sodium silicate solution with 32% concentration and modulus 1.2. Compared to the strength of the sample cured at 50 °C, the strength of the samples cured at 65 °C and 80 °C are higher at 1 d and 3 d, but the same at 7 d. At high temperature, prolonged curing time will decrease the strength. Long precuring at room temperature before application of heat is beneficial for strength development, and there is about 50% increase in strength of the samples cured at 1 d precuring and 2 d elevated temperature as compared to the strengths of the samples cured for 3 d at elevated temperatures or cured for 28 d at room temperature. The main product of reaction in the geopolymeric material is amorphous alkali aluminosilicate gel.
Similar content being viewed by others
References
V D Glukhovsky, G S Rostovskaja, G V Rumyna. High Strength Alag-alkaline Cements[C]. Proc 7 th International Conference on Chemical Communication, Paris, France, 1980
P V Krivenko. Alkaline Cements[C]. International Conference on Alkaline Cement and Concrete, 1994
J Davidovit. Synthesis of New High-temperature Geopolymers for Reinforced Plastics/Composites[C]. Proc PACETE 79, Society of Plastic Engineers, Brookfield, CT, 1979
J Davidovit. Geopolymers: Inorganic Polymeric New Materials[J]. Thermal Analyses. 1991, 37: 1633–1656
J Davidovit. Properties of Geopolymers Cement[C]. Proc 1 st International Conference on Alkaline Cement and Concretes, Ukraine, 1994
J W Phair, J S J Van Denvent. Effect of the Silicate Activator pH on the Microstructural Characteristics of Waste-based Geopolymers[J]. Miner. Process. 2002, 66: 121–143
J G S van Jaarsveld, J S J van Deventer, G C Lukey. The Effect of Composition and Temperature on the Properties of Fly Ash- and Kaolinite-based Geopolymers[J]. Chemical Engineering Journal, 2002, 89: 63–73
K C Goretta, Nan Chen, F Gutierrez, et al. Solid-particle Erosion of a Geopolymer Containing Fly Ash and Blast-furnace Slag[J]. Wear, 2004, 256: 714–719
J G J van Jaarsveld, J S J van Deventer, G C Lukey. The Characterization of Source Materials in Fly Ash-based Geopolymers[J]. Materials Letters. 2003, 57: 1272–1280
T Bakharev. Geopolymeric Materials Prepared Using Class F Fly Ash and Elevated Temperature Curing[J]. Cement and Concrete Research, 2005, 35: 1224–1232
Fernandez-Jimenez, A Palomo, M Criado. Microstructure Development of Alkali-activated Fly Ash Cement: a Descriptive Model[J]. Cement and Concrete Research. 2005, 35: 1204–1209
W Jiang, D Roy. Hydrothermal Processing of New Fly Ash Cement[J]. Ceramal Bull. 1990, 71(4): 642–647
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Hou, Y., Wang, D., Zhou, W. et al. Effect of activator and curing mode on fly ash-based geopolymers. J. Wuhan Univ. Technol.-Mat. Sci. Edit. 24, 711–715 (2009). https://doi.org/10.1007/s11595-009-5711-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11595-009-5711-3