The Influence of the Water/Cement Ratio in the Open Porosity and in the Carbonation Front Advancing in Cementitious Matrix Composites

Abstract:

In this study involving cementitious matrix composites, the influence of the water/cement (w/c) ratio variation (0.48, 0.60, 0.70 and 0.75) was analyzed in its open pore structure and in the carbonation front advancing. Test specimens were molded in cylindrical dimensions of (5x10) cm and (2x4) cm for each mix proportions, and subjected into accelerated carbonation tests, at controlled exposure conditions. The open porosity of the material was obtained by using a helium pycnometer. A model based on Fick's second law was used to fit an equation to the curve of progress of the carbonation front over time. The results show that the water/cement ratio can highly influence the analyzed properties; the mathematical model used provided an excellent approximation of the advancing carbonation front trend, allowing a good evaluation of the carbonation coefficient (K) associated to each mixture proportioning.

• Periodical: Applied Mechanics and Materials (Volume 864)
• Pages: 313-317
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.864.313
• Online since: April 2017
• Authors: Aldo G. Magalhães*, Fernando José Silva, M.A.P. Rezende, White J. Santos, E.V.M. Carrasco, J.N.R. Mantilla, E.M. Piancastelli
• Keywords: Carbonation, CO₂ Diffusion, Porosity, Portland Cement Composite

References

[1] H.F.W. Taylor, Cement Chemistry, second ed., Thomas Telford, London, (1997).

[2] P.C. Hewlett, Lea's Chemistry of Cement and Concrete, fifth ed., Elsevier, Oxford, (2008).

[3] A.M. Neville, Properties of Concrete, fifth ed., Pearson Education Limited, Harlow, England, (2012).

[4] P.K. Mehta, P.J.M. Monteiro, Concrete: Microstructure, Properties and Materials, third ed., McGraw-Hill, (2006).

[5] Q. Pu, L. Jiang, J. Xu, Y. Xu, Y. Zhang, Evolution of pH and chemical composition of pore solutions in carbonated concrete, Construct. Build. Mater. 28(1) (2012) 519-524.

DOI: 10.1016/j.conbuildmat.2011.09.006

[6] V.G. Papadakis, M.N. Fardis, C.G. Vayenas, Effect of composition, environmental factors and cement-lime mortar coating on concrete carbonation, Materials and Structures. 25(5) (1992) 293-304.

DOI: 10.1007/bf02472670

[7] H. Cui, W. Tang, W. Liu, Z. Dong, F. Xing, Experimental study on effects of CO2 concentrations on concrete carbonation and diffusion mechanisms, Construct. Build. Mater. 93 (2012) 522-527.

DOI: 10.1016/j.conbuildmat.2015.06.007

[8] A.V. Saetta, R.V. Vitaliani, Investigation and numerical modeling of carbonation process in reinforced concrete structures, Part I: Theorical formulation, Cem. Concr. Res. 34(4) (2004) 571-579.

DOI: 10.1016/j.cemconres.2003.09.009

[9] S.J. Kwon, H.W. Song, Analysis of carbonation behavior in concrete using neural network algorithm and carbonation modeling, Cem. Concr. Res. 40(1) (2010) 119-127.

DOI: 10.1016/j.cemconres.2009.08.022

[10] S.K. Haghighi, Y. Shao, S. Ghoshal, Mathematical modeling of CO2 uptake by concrete during accelerated carbonation curing, Cem. Concr. Res. 67 (2015) 1-10.

DOI: 10.1016/j.cemconres.2014.07.020

[11] NBR 5733 / EB-2. Associação Brasileira de Normas Técnicas, Cimento Portland de alta resistência inicial. Rio de Janeiro, (1991).

[12] NBR 7214. Associação Brasileira de Normas Técnicas, Areia normal para ensaio de cimento – Especificação. Rio de Janeiro (2012).

[13] ISO 190-12. International Organization for Standardizations, Testing of concrete – Part 12: Determination of the carbonation resistance of concrete – Accelerated carbonation method, (2015).

DOI: 10.3403/30379437u