Journal of the Korean Recycled Construction Resources Institute (한국건설순환자원학회논문집)

Korean Recycled Construction Resources Institute (한국건설순환자원학회)
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Prediction for Pore Structure of Cement Mortar Exposed to Freezing-Thawing Action by Ultrasonic Pulse Velocity Measurement

초음파 속도 측정을 통한 동결·융해 작용을 받는 시멘트 모르타르의 공극 구조 예측

  • Pang, Gi-Sung (Architectural and Environmental System Engineering, Sungkyunkwan University) ;
  • Lee, Kwang-Myong (Architectural and Environmental System Engineering, Sungkyunkwan University)
  • 방기성 (성균관대학교 건설환경시스템공학과) ;
  • 이광명 (성균관대학교 건설환경시스템공학과)
  • Received : 2017.09.22
  • Accepted : 2017.11.16
  • Published : 2017.12.30
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Abstract

In this paper, the effect of freezing-thawing action on the dynamic modulus and porosity was examined by ultrasonic pulse velocity (UPV) measurement. UPV was measured every 30 cycles during the freezing-thawing test, and dynamic modulus and porosity of cement mortar were calculated by relationship among UPV, porosity and dynamic modulus. Porosity analysis was also performed to compare with calculated porosity by mercury intrusion porosimetry (MIP). From the test, it was found that dynamic modulus of cement mortar was decreased 13% after 300 cycles. The calculated porosity was increased about 30% compared with the initial porosity before freezing-thawing action. The calculated porosity showed similar increase tendency with the porosity measured by MIP. So, it can be concluded that the porosity change of cementitious materials by freezing-thawing action can be predicted by UPV measurement.

본 연구에서는 초음파 속도 측정 실험을 이용하여 동결 융해 작용을 받는 시멘트 모르타르의 동탄성 계수 및 공극 구조 변화를 평가하기 위한 연구를 수행하였다. 초음파 속도는 동결융해 시험 중 매 30cycle마다 시편을 꺼낸 후 측정하였으며, MIP를 이용한 porosity 분석도 수행하였다. 초음파 속도 측정 결과를 이용하여 동탄성계수를 계산한 결과 300cycle 이후 약 13%가 감소하는 것으로 나타났다. porosity는 초기에 대비해서 약 30%가량 증가하였으며, 초음파 속도 측정으로부터 계산된 porosity는 MIP를 통해 측정한 porosity와 약 5~30% 차이를 보였지만 유사한 증가 경향을 보이는 것으로 확인되었다. 이를 통해 초음파 속도 측정 결과를 이용하여 시멘트 모르타르의 porosity 변화를 예측하는 것은 타당한 방법으로 볼 수 있으며, 이를 이용하여 확산계수 등 내구성 평가 지수를 예측할 수 있는 것을 확인할 수 있었다.

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References

  1. Kwon, S.J., Na, U.J., Park, S.S., Jung, S.H. (2009). Service lifeprediction of concrete wharves with early-aged crack:Probabilistic approach for chloride diffusion, Structural Safety,31, 75-98. https://doi.org/10.1016/j.strusafe.2008.03.004
  2. Pradhan, B. (2014). Corrosion behavior of steel reinforcementin concrete exposed to composite chloride-sulfate environment,Construction and Building Materials, 72, 398-410. https://doi.org/10.1016/j.conbuildmat.2014.09.026
  3. NT Build 443. Concrete, Hardened: Accelerated Chloride Penetration,Nordtest, Finland, 1995.
  4. NT Build 492. Concrete, Mortar and Cement-based Repair Materials:Chloridemigration Coefficient from Non-steady-state MigrationExperiments, Nordtest, Finland, 1999.
  5. ASTM C 1202. Standard Test Method for Electrical Indication of Concrete's Ability to Resist Chloride Ion Penetration. Annual book of ASTM standards. American Society for Testing and Materials; 2005.
  6. Oh, B.H., Jang, S.Y. (2007). Effects of material and environmental parameters on chloride penetration profiles in concrete structures, Cement and Concrete Research, 37(1), 398-410. https://doi.org/10.1016/j.cemconres.2006.02.004
  7. Choi, Y.C., Park, B., Pang, G.S., Lee, K.M., Choi, S. (2017). Modelling of chloride diffusivity in concrete considering effect of aggregates, Construction and Building Materials, 136, 81-87. https://doi.org/10.1016/j.conbuildmat.2017.01.041
  8. Park, K.P., Kim, S.S., Lee, S.T., Kim, J.P., Jung, H.S. (2011). Properties on the freeze-thaw of concrete subjected to seawater attack, Journal of the Korea Concrete Institute, 23(1), 23-30 [in Korean]. https://doi.org/10.4334/JKCI.2011.23.1.023
  9. Kim, S.W., Choi, K.B., Yun, H.D. (2010). Effect of freeze-thaw cycles after cracking damage on the flexural behavior of reinforced concrete beams, Journal of the Korea Concrete Institute, 22(3), 399-407 [in Korean]. https://doi.org/10.4334/JKCI.2010.22.3.399
  10. Cho, T.J., Kim, L.H., Cho, H.N. (2008). Development of deterioration prediction model and reliability model for the cyclic freeze-thaw of concrete structures, Journal of the Korea Concrete Institute, 20(1), 13-22 [in Korean]. https://doi.org/10.4334/JKCI.2008.20.1.013
  11. Pang, G.S., Chae, S.T. Chang, S.P. (2009). Predicting model for pore structure of concrete including interface transition zone between aggregate and cement paste, International Journal of Concrete Structures and Materials, 3(2), 81-90. https://doi.org/10.4334/IJCSM.2009.3.2.081
  12. Lide, D.R. (2000). CRC Handbook of Chemistry and Physics, 81st Edition. CRC Press, Boca Raton, USA.
  13. Hernandez, M.G., Anaya, J.J., Ullate, L.G., Cegarra, M., Sanchez, T. (2006). Application of a micromechanical model of three phases to estimating the porosity of mortar by ultrasound, Cement and Concrete Research, 36(4), 617-624. https://doi.org/10.1016/j.cemconres.2004.07.018
  14. Kendall, K. (1984). In Physics and Chemistry in Porous Media, Johnson, American Institute of Physics, New York, USA.