Transport in Porous Media

, Volume 14, Issue 3, pp 219–245 | Cite as

The microstructure of porous building materials: Study of a cement and lime mortar

  • P. C. Philippi
  • P. Rosendo Yunes
  • C. P. Fernandes
  • F. S. Magnani


Building materials such as cement mortars and concrets present a very broad distribution of pore sizes, from some tenths of angstroms to several micra. This distribution is very important in establishing their macroscopic properties, e.g., vapor adsorption and desorption and moisture transfer. It is, thus, important to develop procedures to analyze the microstructure of these materials in the full range of pore sizes. In the present work, two complementary methods are used for obtaining the pore sizes distribution of a cement and lime mortar, often used as a building coating material. Electron scanning microscopy is used for pore sizes greater than 1250 å, from a sequence of pictures taken with magnifications from 25x to 12500x, for highly polished surfaces. The heterogeneous spatial distribution of pores is discussed, related to the problem of the geometrical reconstitution of porous structure. For pore sizes smaller than 1250 å, adsorption isotherms obtained at 30 ‡C are used. Molecular physical adsorption is supposed to be the dominant adsorption mechanism in a wide range of relative humidities and modeled using the De Boer and Zwikker theory. This is confirmed by a very high correlation coefficient equal to 0.994 for the present case, for values of RH smaller than 80%. Capillary condensation is supposed to become significant at the point where the adsorption curve deviates from the linear behavior as predicted by the De Boer and Zwikker theory, and the Broekhoff and De Boer theory is used for predicting the pore size distribution from the adsorption isotherm,starting from the deviation point andincreasing RH. The results show the pore size distribution between 200 å and 13Μm.

Key words

Pore sizes distribution sorption isotherms electron scanning microscopy moisture porous building materials 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Adamson, A. W., 1982,Physical Chemistry of Surfaces, John Wiley, New York.Google Scholar
  2. Adler, P. M., Jacquin, C. G. and Quiblier, J. A., 1990, Flow in simulated porous media,Int. J. Multiphase Flow 16, 691–712.Google Scholar
  3. Allen, A. J., 1982, A small-angle-neutron-scattering study of cement porosities,J. Phys. D: Appl. Phys. 35, 1817–1833.Google Scholar
  4. Badmann, R., Stockhausen, N., and Setzer, M. J., 1981, The statistical thickness and the chemical potential of adsorbed water films,J. Coll. Int. Sci. 82, 534–542.Google Scholar
  5. Barret, E. P., Joyner, L. G., and Halenda, P. P., 1951, The determination of the pore volume and area distributions in porous substances. I-Computations from nitrogen isotherms,J. Am. Chem. Soc. 73, 373–380.Google Scholar
  6. Bizot, H., 1983, Using the GAB model to construct sorption isotherms, inPhysical Properties of Foods, Applied Science Publishers, pp. 43–54.Google Scholar
  7. Broekhoff, J. C. P. and De Boer, J. H., 1967, Studies on pore systems on catalysts. IX. Calculation of pore distributions from the adsorption branch of nitrogen sorption isotherms in the case of open cylindrical pores,J. Catalysis 9, 8–14.Google Scholar
  8. Broekhoff, J. C. P. and De Boer, J. H., 1968, Studies on pore systems in catalysts. XII. Pore distribution calculations from the adsorption isotherm in the case of ink-bottle type pores,J. Catalysis 10, 368–376.Google Scholar
  9. Brunauer, S., Emmet, P. H., and Teller, E., 1938, Adsorption of gases in multimolecular layer,J. Am. Chem. Soc.,60, 309–319.Google Scholar
  10. Daian, J. F., 1986, Processus de condensation et de transfert d'eau dans un materiau meso et macroporeux. étude expérimentale du mortier de ciment, Docteur d'état Thesis, Institut National Polytechnique de Grenoble, Grenoble.Google Scholar
  11. Fernandes, C. P. and Philippi, P. C., 1989, Vapour condensation and moisture flow in building coating materials, in J. B. Chaddock and B. Todorovic (eds),Proceedings of ICHMT Symposium on Heat and Mass Transfer in Building Materials and Structure, Dubrovnik, Yugoslavia, pp. 29–42.Google Scholar
  12. Jennings, H. M., 1988, Design of high strength cement based materials: Part 2 microstructure,Mat. Sci. Technol. 4, 285–290.Google Scholar
  13. Knab, L. I., Walker, H. N., Clifton, J. R., and Fuller Jr, E. R., 1984, Fluorescent thin sections to observe the fracture zone in mortar,Cem. Concr. Res.,14, 339–344.Google Scholar
  14. Lange, D. A., Jennings, H. M., Shah, S. P., and Quenard, D., 1990, A fractal approach to understanding cement paste microstructure, inAdvances in Cementitious Materials, Washington.Google Scholar
  15. Mandelbrot, B. B., 1982,The Fractal Geometry of Nature, W. H. Freeman, New York.Google Scholar
  16. Mason, G., 1982, The effect of pore space connectivity on the hysteresis of capillary condensation in adsorption-desorption isotherms,J. Coll. Int. Sci. 88, 36–46.Google Scholar
  17. Merrouani, L., 1987, Phenomènes de sorption et de transfert d'humidité dans des materiaux du bâtiment, étude expérimentale comparative d'un mortier de ciment et d'un enduit de faÇade, Docteur 3eme Cycle Thesis, Institut National Polytechnique de Grenoble, Grenoble.Google Scholar
  18. Neimark, A. V., 1986, A percolation method for calculating the pore size distribution in materials of intermediate porosity based on the adsorption and desorption isotherms in the hysteresis region,Russian J. Phys. Chem. 60, 1045–1048.Google Scholar
  19. Paulon, V. A. and Monteiro, P. J. M., 1991, Estudo da microestrutura da zona de transiÇÃo entre a pasta de cimento e o agregado,Boletim Técnico BT/PCC/43, Universidade de SÄo Paulo, SÃo Paulo.Google Scholar
  20. Pearson, D., Allen, A. J., Windsor, C. G., Mc Alford, N., and Double, D. D., 1983, An investigation on the nature of porosity of cement pastes using small-angle-neutron-scattering,J. Mat. Sci.,18, 430–438.Google Scholar
  21. Pearson, D. and Allen, A. J., 1985, A study of ultra-fine porosity in hydrated cement pastes using small-angle-neutron-scattering,J. Mat. Sci. 20, 303–315.Google Scholar
  22. Pedrini, A., Philippi, P. C., Cruz, J. A., and Fernandes, C. P., 1990, Technical Report 03/90: Characterization of consolidated porous materials, EMC/UFSC, Florianópolis.Google Scholar
  23. Perrin, B., 1985, Etude des transferts couplés de chaleur et de masse dans des materiaux poreux consolidés non-saturés utilisés en génie civil, Paul Sabatier University, Toulouse, Docteur d'Etat Thesis.Google Scholar
  24. Quadri, M., 1988, Dinâmica de resposta de tensiÔmetros: Desenvolvimento experimental e modelaÇÃo numérica, Departamento de Engenharia Mecânica da UFSC, Florianópolis, Tese de Mestrado.Google Scholar
  25. Quenard, D., 1989, Adsorption et transfert d'humidité dans les materiaux hygrocopiques, Institut National Polytechnique de Toulouse, Toulouse, Doctoral Thesis.Google Scholar
  26. Quiblier, J. A., 1984, A new three-dimensional modeling technique for studying porous media,J. Coll. Int. Science 98, 84–102.Google Scholar
  27. Saliba, J., 1990, Proprietés de transfert hydrique du mortier de ciment: Modélisation à l'échele microscopique; étude à l'échele macroscopique des effets dynamiques des héterogeneités, Institut National Polytechnique de Grenoble, Grenoble, Doctoral Thesis.Google Scholar
  28. Van der Kooi, J., 1971, Moisture transport in cellular concrete roofs, Eindhoven University, Eindhoven, Doctoral Thesis.Google Scholar
  29. Wall, G. C. and Brown, R. J. C., 1981, The determination of pore size distribution from sorption isotherms and mercury penetration in interconnected pores: the application of percolation theory,J. Coll. Int. Sci. 82, 141–149.Google Scholar
  30. Winslow, D. N. and Lovell, C. W., 1981, Measurement of pore size distributions in cements, aggregate and soils,Powder Technol. 29, 151–165.Google Scholar

Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • P. C. Philippi
    • 1
  • P. Rosendo Yunes
    • 1
  • C. P. Fernandes
    • 1
  • F. S. Magnani
    • 1
  1. 1.Mechanical Engineering DepartmentFederal University of Santa CatarinaFlorianópolis, SCBrazil

Personalised recommendations