Hydration and Mechanical Properties of Magnesia, Pulverized Fuel Ash, and Portland Cement Blends
Publication: Journal of Materials in Civil Engineering
Volume 20, Issue 5
Abstract
A study was conducted to determine the quantity of water bound by hydration, the products formed during hydration, the microstructures, and the mechanical properties as a function of the relative content of reactive magnesium oxide (magnesia, MgO), pulverized fuel ash (pfa), portland cement (PC), and water used to prepare the mixes. It was confirmed that hydration of MgO leads to the formation of brucite and that PC forms its normal hydration products, even when both materials are present together. It was found that calculated changes in porosity and consumption of water during hydration based on the proposed hydration reactions agree well with the measurements. It was also found that the stiffness and strength improve directly proportional to the PC content. It is proposed that the lower strength of mixes with high reactive MgO contents is due to a combination of their high water demand and the difference in morphology between brucite and C–S–H gel.
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Acknowledgments
The work presented in this paper is the initial part of an extensive research programme being carried out as part of a U.K. Engineering and Physical Sciences Research Council (EPSRC)EPSRC-GB funding as a core Mini-Waste Faraday Partnership project entitled “Waste minimization through sustainable magnesium oxide cement products.” The project is led by Cambridge University and carried out in collaboration with Imperial College London and MIT, United States, and ten industrial collaborators including the inventor of the MgO cement technology John Harrison of TecEco Pty Ltd., Australia. The financial support provided by EPSRC, under Grant No. EPSRC-GBGR/T26870/01, is gratefully acknowledged. The support from the Mini-Waste Faraday Partnership is also gratefully acknowledged. The writers are also grateful to Nikolaos Vlasopoulos at Imperial College for the measurements of specific surface area and particle sizes.
References
Ahari, K. G., Sharp, J. H., and Lee, W. E. (2002). “Hydration of refractory oxides in castable bond systems. I: Alumina, magnesia, and alumina-magnesia mixtures.” J. Eur. Ceram. Soc., 22(4), 495–503.
Alford, N. M., Birchall, J. D., Howard, A. J., and Kendall, K. (1985). “Comments on ‘The factors affecting strength of portland cement.’ ” J. Mater. Sci., 20, 1134–1136.
ASTM. (2001). Standard test method for dynamic Young’s modulus, shear modulus, and Poisson’s ratio for advanced ceramics by impulse excitation, ASTM C1259-01, Philadelphia.
Brew, D. R. M., and Glasser, F. P. (2005). “Synthesis and characterisation of magnesium silicate hydrate gels.” Cem. Concr. Res., 35, 85–98.
British Standards Institution (BSI). (1997). “Part 1: Specification for pulverized-fuel ash for use with portland cement.” BS 3892, London.
British Standards Institutions (BSI). (2002). “Testing hardened concrete. Part 3: Compressive strength of test specimens.” BS EN 12390, London.
Harrison, J. (2001). Reactive magnesium oxide cements, WO 01/55049 A1.
Harrison, J. (2003). “New cements based on the addition of reactive magnesia to portland cement with or without added pozzolan.” Proc., CIA Conf.: Concrete in the Third Millennium, CIA, Brisbane, Australia.
Hewlett, P. C. (1998). Lea’s chemistry of cement and concrete, Arnold, London.
Kendall, K., Howard, A. J., Birchall, J. D., Pratt, P. L., Proctor, B. A., and Jefferis, S. A. (1983). “The relation between porosity, microstructure and strength, and the approach to advanced cement-based materials.” Philos. Trans. R. Soc. London, Ser. A, 310(1511), 139–153.
Lokhorst, S. J., and van Breugel, K. (1997). “Simulation of the effect of geometrical changes of the microstructure on the deformational behaviour of hardening concrete.” Cem. Concr. Res., 27(10), 1465–1479.
Mindess, S., Young, J. F., and Darwin, D. (2003). Concrete, Prentice-Hall, Upper Saddle River, N.J.
Pearce, F. (1997). “The concrete jungle overheats.” New Sci., 155(2091), 14.
Pettala, V. E. (1992). “Nature of compression strength in concrete.” Mag. Concrete Res., 44(159), 87–106.
Rößler, M., and Odler, I. (1985). “Investigations on the relationship between porosity, structure and strength of hydrated portland cement pastes. I: Effect of porosity.” Cem. Concr. Res., 15(2), 320–330.
Van Oss, H., ed. (2005). “Mineral commodity summaries.” Survey USG, 42–43.
Wesche, K. (1991). Fly ash in concrete: Properties and performance, Chapman and Hall, London.
Information & Authors
Information
Published In
Journal of Materials in Civil Engineering
Volume 20 • Issue 5 • May 2008
Pages: 375 - 383
Copyright
© 2008 ASCE.
History
Received: Jan 9, 2007
Accepted: Apr 11, 2007
Published online: May 1, 2008
Published in print: May 2008
Notes
Note. Associate Editor: Chiara F. Ferraris
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