Journal of the Korea Concrete Institute (콘크리트학회논문집)

Korea Concrete Institute (한국콘크리트학회)
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Sulfate Attack Resistance and Microstructural Observations of Cement Matrix Exposed to a Low Temperature Condition

저온환경에 노출된 시멘트 경화체의 황산염침식 저항성 및 미세구조적 조사

  • Published : 2009.10.31
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Abstract

This paper reports an experimental study on the damage mechanism and resistance of Type I portland cement mortar and paste samples exposed to 5% sodium sulfate solution with different solution temperatures; namely, $4^{\circ}C$, $10^{\circ}C$ and $20^{\circ}C$. The resistance of mortar samples was evaluated using expansion, compressive strength and flexural strength measurements. Some microstructural observations such as x-ray diffraction, differential scanning calorimetry and scanning electron microscopy were also introduced to elucidate reactants formed by sulfate attack, especially in a low temperature condition. From the results, it was found that the degree of damage in the mortar samples was significantly associated with the temperature of sulfate solution. Low temperature of the sulfate solution led to the formation of thaumasite in mortar and paste samples, and subsequently a poor resistance to sulfate attack. Thus, it is noted that when concrete structures are exposed to sulfate media in the condition of a cold region or whether, special care should be taken.

이 연구는 보통포틀랜드시멘트로 제조된 모르타르 및 페이스트 샘플의 황산염침식 저항성을 평가하기 위하여 수행되었다. 주요 실험변수는 사용된 황산염용액의 온도조건으로써, 각각 $4^{\circ}C$, $10^{\circ}C$ 및 $20^{\circ}C$로 유지된 5% 황산나트륨 용액에 침지한 모르타르의 침지재령별 팽창, 압축강도 및 휨강도를 측정 한 후, 황산염침식 저항성을 평가하였다. 뿐만 아니라, XRD, DSC 및 SEM/EDS와 같은 기기분석 기법을 이용하여 저온환경에 노출된 페이스트 샘플 중에 생성된 반응생성물 조사 및 미세구조 분석도 아울러 실시하였다. 실험 결과에 의하면, 황산염침식에 의한 모르타르의 성능 저하는 시험용액 온도에 매우 의존적으로 나타났으며, 특히, 저온환경에서는 쏘마싸이트의 생성으로 인한 성능 저하가 매우 극심하게 나타남을 확인할 수 있었다. 따라서, 저온의 황산염환경에 콘크리트구조물이 노출될 경우 세심한 주의가 요구된다.

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References

  1. Brown, P. W. and Doerr, A., "Chemical Changes in Concrete Due to the Ingress of Chemical Species," Cement and Concrete Research, Vol. 30, No. 3, 2000, pp. 411-418 https://doi.org/10.1016/S0008-8846(99)00266-5
  2. RILEM Technical Committee TC 116-PCD, Performance Criteria for Concrete Durability, 1995, pp. 97-98
  3. Hime, W. G. and Mather, B., "Sulfate Attack, or Is It ?," Cement and Concrete Research, Vol. 29, No. 5, 1999, pp. 789-791 https://doi.org/10.1016/S0008-8846(99)00068-X
  4. Fiskaa, O., Hansen, H., and Moum, J., "Concrete in Alum Shale," Norweigian Geotechnical Institute, Publication, Oslo, No. 86, 1971, 32 pp
  5. Jallad, K. N., Santhanam, M., and Cohen, M. D., "Stability and Reactivity of Thaumasite at Different pH Levels," Cement and Concrete Research, Vol. 33, No. 3, 2003, pp. 433-437 https://doi.org/10.1016/S0008-8846(02)00971-7
  6. Hartshorn, S., A., Sharp, J. H., and Swamy, R. N., "Thaumasite Formation in Portland-Limestone Cement Pastes," Cement and Concrete Research, Vol. 29, No. 8, 1999, pp. 1331-1340 https://doi.org/10.1016/S0008-8846(99)00100-3
  7. Akoz, F., Turker, F., Koral, S., and Yuzer, N., "Effects of Raised Temperature of Sulfate Solutions on the Sulfate Resistance of Mortars with and without Silica Fume," Cement and Concrete Research, Vol. 29, No. 4, 1999, pp. 537-544 https://doi.org/10.1016/S0008-8846(98)00251-8
  8. Mangat, P. S. and El-Khatib, J. M., "Influence of Initial Curing on Sulphate Resistance of Blended Cement Concrete," Cement and Concrete Research, Vol. 22, No. 6, 1992, pp. 1089-1100 https://doi.org/10.1016/0008-8846(92)90039-X
  9. Crammond, N. J. and Halliwell, M. A., "The Thaumasite Form of Sulfate Attack in Concretes Containing a Source of Carbonate Ions," In 2nd Symposium Advances in Concrete Technology, ACI SP-154, 1995, pp. 357-380
  10. Collepardi, M., "Deterioration and Restoration of Masonry Walls of Historical Buildings," Materials and Structures, Vol. 23, No. 2, 1990, pp. 81-102 https://doi.org/10.1007/BF02472568
  11. Berra, M. and Baronio, G., "Thaumasite in Deteriorated Concretes in the Presence of Sulfates," Concrete Durability, ACI SP-100, 1987, pp. 2073-2089
  12. Ludwig, U. and Meher, S., "Destruction of Historical Building by the Formation of Ettringite and Thaumasite,S In Proceedings of 8 th International Congress on the Chemistry of Cement, Rio de Janeiro, Brazil, 1986, pp. 181-188
  13. Bickley, J. A., Hemmings, R. T., and Hooton, R. D., "Thaumasite Related Deterioration of Concrete Structures," ACI Sp-144, 1994, pp. 159-175
  14. Diamond, S., "Thaumasite in Orange Country, Southern California: an Inquiry into the Effect of Low Temperature," Cement and Concrete Composite, Vol. 25, No. 8, 2003, pp. 1161-1164 https://doi.org/10.1016/S0958-9465(03)00138-0
  15. Irassar, E. F., Gonzalez, M., and Rahhal, V., "Sulphate Resistance of Type V Cements with Limestone Filler and Natural Pozzolana," Cement and Concrete Composites, Vol. 22, No. 5, 2002, pp. 361-368 https://doi.org/10.1016/S0958-9465(00)00019-6
  16. Hartshorn, S. A., Sharp, J. H., and Swamy, R. N., "The Thaumasite Form of Sulfate Attack in Portland-Limestone Cement Mortars Stored in Magnesium Sulfate Solution," Cement and Concrete Composites, Vol. 24, No. 3, 2002, pp. 351-359 https://doi.org/10.1016/S0958-9465(01)00087-7
  17. Mehta P. K., Material Science of Concrete , Jan Skalny, Ed., American Ceramic Society, 1992, pp. 102-130
  18. Moon, H. Y., Lee, S. T., and Kim, S. S., "Sulphate Resistance of Silica Fume Blended Mortars Exposed to Various Sulphate Solutions," Canadian Journal of Civil Engineering, Vol. 30, No. 4, 2003, pp. 625-636 https://doi.org/10.1139/l03-024
  19. Al-Amoudi, O. S. B., Maslehuddin, M., and Saadi, M. M., "Effect of Magnesium Sulfate and Sodium Sulfate on the Durability Performance of Plain and Blended Cements," ACI Materials Journal, Vol. 92, No. 1, 1995, pp. 15-24
  20. Wee. T. H. et al., "Sulfate Resistance of Concrete Containing Mineral Admixtures," ACI Materials Journal, Vol. 97, No. 5, 2000, pp. 536-549
  21. Tian, B. and Cohen, M. D., "Does Gypsum Formation During Sulfate Attack on Concrete Lead to Expansion?," Cement and Concrete Research, Vol. 30, No. 1, 2000, pp. 117-123 https://doi.org/10.1016/S0008-8846(99)00211-2