Hostname: page-component-7c8c6479df-24hb2 Total loading time: 0 Render date: 2024-03-28T19:01:08.525Z Has data issue: false hasContentIssue false

Modelling approach to the prediction of Equilibrium Phase Distribution in Slag-Cement Blends and their Solubility Properties.

Published online by Cambridge University Press:  28 February 2011

Frederik P. Glasser
Affiliation:
Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, AB9 2UE, Scotland.
Donald E. Macphee
Affiliation:
Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, AB9 2UE, Scotland.
Eric E. Lachowski
Affiliation:
Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, AB9 2UE, Scotland.
Get access

Abstract

Blended cements containing mixtures of granulated blast-furnace slag (BFS) and Portland cement give low permeability matrices with initially favourable leach characteristics. Their retention arises from a combination of physical and chemical effects which include high pH and sorption. It is not practical though, in either laboratory or site-based experimentation, to determine changes in matrix chemistry over long timescales and the development of realistic models for long-term property predictions therefore becomes increasingly important. This paper pursues the development of such a model enabling changes in chemical and mineralogical balances during ageing to be predicted.

Phase development is assessed in the system CaO-Al2O3-SiO2-MgO-H2O. In the relevant composition range, the phases occurring include crystalline hydrates: portlandite, (Ca(OH)2); gehlenite hydrate, (2CaO.Al2O3.SiO2.8H2O); a hydrotalcite-structured phase (nominally 6MgO.Al2O3.(OH)x.yH2O). an AFm type phase, (nominally 4CaO.Al2O3 SO3.12H2O); and a poorly crysiallised c~lcium silicate hydrogel, C-S-H. All five phases are observed to occur together in slag-cements which are still hydrating. Given, as input, the chemical analyses of both the slag and the cement, and the initial blending proportions, the model predicts the equilibrium distribution between the five components and additionally, the Ca/Si ratio of the C-S-H. The aqueous chemistry in the system is predicted from the calculated phase distribution and appropriate solubility products.

Type
Research Article
Copyright
Copyright © Materials Research Society 1988

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Glasser, F.P, Macphee, D.E. and Lachowski, E.E., Proc. Mat. Res. Soc., 84, 331, (1987).CrossRefGoogle Scholar
2. Wilding, C.R. and McHugh, G., AERE R 12297, (1986).Google Scholar
3. Roy, D.M., Sonnenthal, E. and Prave, R., Cem. Concr. Res., 15, 914, (1985).CrossRefGoogle Scholar
4. Luke, K. (personal communication), (1987).Google Scholar
5. Dron, R., Proc. IV th Int. Cong. Chem. Cem. (Moscow), 11−2,3,4, (1974).Google Scholar
6. Lachowski, E.E., Mohan, K., Taylor, H.F.W. and Moore, A.E., J. Am. Ceram. Soc., 63, 447, (1980).CrossRefGoogle Scholar
7. Taylor, H.F.W., Cem. Res. Progress, Chapter 5, 91, (1984).Google Scholar
8. Taylor, H.F.W., Proc. VII th Int. Cong. Chem. Cem. (Rio de Janeiro), (1986).Google Scholar
9. Mascolo, G., Cem. Concr. Res., 3, 207, (1973).CrossRefGoogle Scholar
10. Mascolo, G., Cem. Concr. Res., 16, 610, (1986).CrossRefGoogle Scholar
11. Mascolo, G. and Marino, O., Mineral. Mag., 43, 619, (1980).CrossRefGoogle Scholar
12. Brindley, G.A. and Kikkawa, S., Amer. Mineral., 64, 836, (1979).Google Scholar
13. Greenberg, S.A., Chang, T.N. and Anderson, E., J. Phys. Chem., 64, 1151, (1960).CrossRefGoogle Scholar
14. Kantro, D.L., Brunauer, S. and Weise, C.H., J. Phys. Chem., 66, 1804, (1962).CrossRefGoogle Scholar
15. Greenberg, S.A. and Chang, T.N., J. Phys. Chem., 69, 182, (1965).CrossRefGoogle Scholar
16. Taylor, H.F.W., J. Chem. Soc., 1950, 3682.CrossRefGoogle Scholar
17. Fujii, K. and Kondo, W., J. Chem. Soc., Dalton Trans., 2, 645, (1981).CrossRefGoogle Scholar
18. D'Ans, J. and Eick, H., Zement Kalk Gips, 6, 197, (1953).Google Scholar
19. Bates, R.G., Bowers, V.E. and Smith, E.R., J. Res. Nat. Bur. Stand., 56, 305, (1956).CrossRefGoogle Scholar
20. Berner, U.R., presented at “Migration '87”, Munich, 1987 (unpublished).Google Scholar
21. Brown, P.W., Franz, E., Frohnsdorff, G. and Taylor, H.F.W., Cem. Concr. Res., 14, 257, (1984).CrossRefGoogle Scholar
22. Berner, U.R., Proo. Mat. Res. Soc.,84, 319, (1987).CrossRefGoogle Scholar