Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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Distribution of Calcium Hydroxide at the ITZ between Steel and Concrete

  • Ann Ki-Yong (Dept. of civil and Environmental Engineering, imperial College) ;
  • Kim Hong-Sam (Dept. of civil Engineering, Hanyang University) ;
  • Kim Yang-Bae (Dept. of civil Engineering, Hanyang University) ;
  • Moon Han-Young (Dept. of civil Engineering, Hanyang University)
  • Published : 2005.06.01
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Abstract

The present study examines the distribution of calcium hydroxide, unhydrated cement grain and porosity at the steel-concrete interface. The formation of calcium hydroxide has been confirmed by microscopic analysis using BSE images containing the ITZ between the steel and concrete. It was found that calcium hydroxide does not form a layer on the steel surface, different from the hypothesis that has been available in investigating the corrosion of steel in concrete, ranging from 5 to $10\%$ within the steel surface. Moreover, the high level of porosity at the ITZ was observed, accounting for $30\%$, which may reduce the buffering capacity of cement hydration products against a local fall in the pH. These findings may imply that the mole of ($Cl^-$) :($OH^-$) in pore solution as chloride threshold level lead to wrong judgement or to a wide range of values.

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References

  1. G.K. Glass, B. Reddy, and N.R. Buenfeld, 'Corrosion inhibition in concrete arising from its acid neutralisation capacity', Corrosion Science 42, 2000, pp.1587-1598 https://doi.org/10.1016/S0010-938X(00)00008-1
  2. G.K. Glass, B. Reddy, and N.R. Buenfeld, 'The participation of bound chloride in passive film breakdown on steel in concrete', Corrosion Science 42, 2000, pp.2013-2021 https://doi.org/10.1016/S0010-938X(00)00040-8
  3. C.L. Page, 'Mechanism of corrosion protection in reinforced concrete marine structure', Nature 256, 1975, pp.514-515
  4. U. A. Birnin-Yauri and F. P. Glasser, 'Friedel's salt, $Ca_2Al(OH)_6(Cl,OH).2H_2O$: its solid solutions and their role in chloride binding', Cement and Concrete Research, Vol.28, No.12., 1998, pp.1713-1723 https://doi.org/10.1016/S0008-8846(98)00162-8
  5. G. K. Glass, R. Yang, T. Dickhaus, and N.R. Buenfeld, 'Back-scattered electron imaging of the steel-concrete interface', Corrosion Science 43, 2001, pp.605-610 https://doi.org/10.1016/S0010-938X(00)00146-3
  6. M. K. Head, Influence of the interfacial transition zone (ITZ) of properties of concrete, PhD Thesis, University of Leeds, 2001, pp.63-118
  7. A. R. Brough and A. Atkinson, 'Automated identification of the aggregate-paste interfacial transition zone in mortars of silica sand with Portland or alkali-activated slag cement paste', Cement and Concrete Research, Vol.30, No.6., 2000, pp.849-854 https://doi.org/10.1016/S0008-8846(00)00254-4
  8. K. L. Scrivener and K. M. Nemati, 'The percolation of pore space in the cement paste/aggregate interfacial zone of concrete', Cement and Concrete Research, Vol.26, No.1., 1996, pp.35-40 https://doi.org/10.1016/0008-8846(95)00185-9
  9. K. L. Scrivener and E. M. Gartner, 'Microstructural gradients in cement paste around aggregate particles, In: Bonding in cementitious composite', S. Mindness and S.P. Shah eds., Materials Research Society, Issue 114, 1988, pp.77-86
  10. K L. Scrivener, A. K. Crumbie, and P. L. Pratt, 'A study of the interfacial region between cement paste and aggregate in concrete, In: Bonding in cementitious composite, S. Mindness and S.P. Shah eds.', Materials Research Society, Issue 114, 1988, pp.87-88
  11. S. Diamond, 'Considerations in image analysis as applied to investigations of the ITZ in concrete', Cement and Concrete Composites, Vol.23, No.1., 2001, pp.171-178 https://doi.org/10.1016/S0958-9465(00)00085-8
  12. K. L. Scrivener and K. M. Nemati, 'The percolation of pore space in the cement paste/aggregate interfacial zone of concrete', Cement and Concrete Research, Vol.26, No.1., 1996, pp.35-40 https://doi.org/10.1016/0008-8846(95)00185-9
  13. G. Sergi and G. K. Glass, 'A method of ranking the aggressive nature of chloride contaminated concrete', Corrosion Science 42, 2000, pp.2043-2049 https://doi.org/10.1016/S0010-938X(00)00050-0
  14. C. L. Page and K. W. J. Treadaway, 'Aspects of the electro-chemistry of steel in concrete', Nature 297, 1982, pp.109-115 https://doi.org/10.1038/297109a0
  15. T. U. Mohammed, N. Otsuki, and M. Hisada, 'Corrosion of steel bars with respect to orientation of concrete', ACI Material Journal, Vol.96, No.2., 1999, pp.154-159
  16. A. Castel, T. Vidal, R. Francois, and G. Arliguie, 'Influence of steel-concrete interface quality on reinforcement corrosion induced by chlorides', Magazine of Concrete Research, Vol.55, No.2., 2003, pp.151-159 https://doi.org/10.1680/macr.2003.55.2.151
  17. T.A. Soylev and R. Francois, 'Quality of steel-concrete interface and corrosion of reinforcing steel', Cement and Concrete Research, Vol.33, No.9, 2003, pp.1407-1415 https://doi.org/10.1016/S0008-8846(03)00087-5
  18. K.Y. Ann, Enhancing the chloride threshold level for steel corrosion in concrete, PhD Thesis, University of London, 2005, pp.119-177
  19. V. K. Gouda and W.Y. Halaka, 'Corrosion and corrosion inhibition of reinforced steel', British Corrosion Journal, Vol.5, No.2., 1970, pp.204-208 https://doi.org/10.1179/000705970798324478
  20. C. Alonso, M. Castellote, and C. Andrade, 'Chloride threshold dependence of pitting potential of reinforcements', Electro-chemica Acta 47, 2002, pp.3469-3481 https://doi.org/10.1016/S0013-4686(02)00283-9
  21. S. Goni and C. Andrade, 'Synthetic concrete pore solution chemistry and rebar corrosion in the presence of chloride', Cement and Concrete Research, Vol.20, No.4., 1990, pp.525-539 https://doi.org/10.1016/0008-8846(90)90097-H