The Effect of Activators on the Fly Ash-Based Geopolymers

Abstract:

This paper studies the influences of concentration and modulus of sodium silicate solution (Na activator) and sodium potassium silicate solution (Na-K activator) on the phase composition, microstructure and strength development in the geopolymers prepared using Class F fly ash. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and MAS NMR were utilized. It shows that the compressive strength increases while Na activator solution modulus increases, but when modulus exceeds 1.4, the compressive strength decreases, and it decreases markedly while modulus is greater than 2.0. The compressive strength improves with increase of sodium silicate solution concentration, and when concentration is 32%, compressive strength reaches the maximum, and then it reduces with concentration increment. It shows that the compressive strength increases while Na-K activator solution modulus increases, but when modulus exceeds 1.7, the compressive strength decreases, and it decreases markedly while modulus is greater than 2.0. The compressive strength improves with increase of Na-K activator solution concentration, and when concentration is 36%, compressive strength reaches the maximum. The main product of reaction in the geopolymeric material is amorphous alkali aluminosilicate gel.

• Periodical: Key Engineering Materials (Volume 477)
• Pages: 85-90
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.477.85
• Online since: April 2011
• Authors: Yun Fen Hou, Dong Min Wang
• Keywords: Compressive Strength, Fly Ash (FA), Geopolymer, Na Activator, Na-K Activator

References

[1] V.D. Glukhovsky, G.S. Rostovskaja, G.V. Rumyna: Proc 7th International Conference on Chemical Communication, Paris, France, (1980).

[2] P.V. Krivenko: International Conference on Alkaline Cement and Concrete, (1994).

[3] J. Davidovit: Proc PACETE 79, Society of Plastic Engineers, Brookfield, CT, (1979).

[4] J. Davidovit: Thermal Analyses (1991), 37: 1633-1656.

[5] J. Davidovit: Proc 1ST International Conference on Alkaline Cement and Concretes, Ukraine, (1994).

[6] J.W. Phair, J.S.J. Van Denvent: Miner. Process. (2002), 66: 121-143.

[7] J.G.S. Van Jaarsveld, J.S. J Van Deventer, G.C. Lukey: Chemical Engineering Journal, (2002), 89: 63-73.

[8] K.C. Goretta, Nan Chen, F. Gutierrez etc.: Wear, (2004), 256: 714-719.

[9] J.G.J. Van Jaarsveld, J.S.J. Van Deventer, G.C. Lukey: Materials Letter, s (2003), 57: 1272-1280.

DOI: 10.1016/s0167-577x(02)00971-0

[10] T. Bakharev: Cement and Concrete Research, (2005), 35: 1224-1232.

[11] Fernandez-Jimenez, A. Palomo, M. Criado: Cement and Concrete Research, (2005), 35: 1204-1209.