Journal of the Korean Recycled Construction Resources Institute (한국건설순환자원학회논문집)

Korean Recycled Construction Resources Institute (한국건설순환자원학회)
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Modified-stoichiometric Model for Describing Hydration of Alkali-Activated Slag

알칼리 활성 슬래그의 수화에 대한 개선된 화학양론적 모델

  • Received : 2020.08.23
  • Accepted : 2020.10.18
  • Published : 2021.03.30
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Abstract

The present study proposes the modified-stoichiometric model for describing hydration of sodium silicate-based alkaliactivated slag(AAS), and compares the results with the thermodynamic modelling-based calculations. The proposed model is based on Chen and Brouwers(2007a) model with updated database as reported in recent studies. In addition, the calculated results for AAS are compared to those for hydrated portland cement. The maximum difference between the proposed model and the thermodynamic calculation for AAS was at most 20%, and the effects of water-to-binder ratio and activator dosages were identically described by both approaches. In particular, the amount of non-evaporable water was within 10% difference, and was in excellent agreement with the experimental results. Nevertheless, notable deviation was observed for the chemical shrinkage, which is largely dependent on the volume of hydrates and pores.

본 연구에서는 가장 대표적인 AAM 중 하나인 규산나트륨 적용 AAS의 수화물 구성에 대한 화학양론 모델을 개발하고, 이 결과를 열역학적 모델 결과와 비교하였다. 기본적으로 Chen and Brouwers(2007a)의 모델을 기반으로 하였으며, 일부 수화물에 대한 최신의 데이터베이스를 적용해 일부 개선하였다. 계산된 AAS에 대한 결과는 또한 OPC의 그것과도 비교되었다. AAS의 화학양론 모델 기반 수화물의 부피 구성비는 열역학적 모델 결과에 비해 약 최대 20% 이내에서의 차이가 발견되었으며, w/b 및 활성화제량에 의한 변화량의 추이 역시 열역학적 모델의 결과의 그것과 거의 동일하였다. 특히 고정수량과 공극비는 두 가지 모델에 의한 계산 결과가 약 10% 이내의 차이로 근접하였다. 특히 고정수량의 결과는 실험값과도 거의 동일하였다. 그러나 수화물 및 기타 공극 등 각 상들의 부피에 의해 민감하게 결정되는 값인 화학수축의 경우 열역학적 모델에 비해 화학양론적 모델의 계산결과는 실험결과와 차이가 컸다.

Keywords

References

  1. Brouwers, H.J.H. (2011). A hydration model of Portland cement using the work of Powers and Brownyard.
  2. Chen, W., Brouwers, H.J.H. (2007a). The hydration of slag, part 1: reaction models for alkali-activated slag, Journal of Materials Science, 42(2), 428-443. https://doi.org/10.1007/s10853-006-0873-2
  3. Chen, W., Brouwers, H.J.H. (2007b). The hydration of slag, part 2: reaction models for blended cement, Journal of Materials Science, 42(2), 444-464. https://doi.org/10.1007/s10853-006-0874-1
  4. Gawin, D., Pesavento, F., Schrefler, B.A. (2006). Hygro-thermo-chemo-mechanical modelling of concrete at early ages and beyond. part I: hydration and hygro-thermal phenomena, International Journal for Numerical Methods in Engineering, 67(3), 299-331. https://doi.org/10.1002/nme.1615
  5. Haha, M.B., Le Saout, G., Winnefeld, F., Lothenbach, B. (2011). Influence of activator type on hydration kinetics, hydrate assemblage and microstructural development of alkali activated blast-furnace slags, Cement and Concrete Research, 41(3), 301-310. https://doi.org/10.1016/j.cemconres.2010.11.016
  6. Jennings, H.M., Xi, Y. (1993). Microstructurally Based Mechanisms for Modeling Shrinkage of Cement Paste at Multiple Levels(No. CONF-9309242-1), Northwestern Univ., Evanston, IL (United States).
  7. Kim, H.J., Tafesse, M., Lee, H.K., Kim, H.K. (2019). Incorporation of CFBC ash in sodium silicate-activated slag system: modification of microstructures and its effect on shrinkage, Cement and Concrete Research, 123, 105771. https://doi.org/10.1016/j.cemconres.2019.05.016
  8. Komljenovic, M., Bascarevic, Z., Marjanovic, N., Nikolic, V. (2013). External sulfate attack on alkali-activated slag, Construction and Building Materials, 49, 31-39. https://doi.org/10.1016/j.conbuildmat.2013.08.013
  9. Lee, H.K., Kim, H.K. (2018). Influence of drying methods on measurement of hydration degree of hydraulic inorganic materials: 1) ordinary portland cement paste and mortar, Journal of the Korean Institute of Resources Recycling, 27(1), 92-105 [in Korean]. https://doi.org/10.7844/kirr.2018.27.1.92
  10. Lee, H.K., Song, K.I., Song, J., Kim, H.K. (2018). Influence of drying methods on measurement of hydration degree of hydraulic inorganic materials: 2) alkali-activated slag, Journal of the Korean Institute of Resources Recycling, 27(1), 106-117 [in Korean]. https://doi.org/10.7844/kirr.2018.27.1.106
  11. Lothenbach, B., Kulik, D.A., Matschei, T., Balonis, M., Baquerizo, L., Dilnesa, B., ... Myers, R.J. (2019). Cemdata18: a chemical thermodynamic database for hydrated portland cements and alkali-activated materials, Cement and Concrete Research, 115, 472-506. https://doi.org/10.1016/j.cemconres.2018.04.018
  12. Lothenbach, B., Winnefeld, F. (2006). Thermodynamic modelling of the hydration of Portland cement, Cement and Concrete Research, 36(2), 209-226. https://doi.org/10.1016/j.cemconres.2005.03.001
  13. Luukkonen, T., Abdollahnejad, Z., Yliniemi, J., Kinnunen, P., Illikainen, M. (2018). One-part alkali-activated materials: A review, Cement and Concrete Research, 103, 21-34. https://doi.org/10.1016/j.cemconres.2017.10.001
  14. Myers, R.J., Bernal, S.A., Provis, J.L. (2014). A thermodynamic model for C-(N-) ASH gel: CNASH_ss. Derivation and validation, Cement and Concrete Research, 66, 27-47. https://doi.org/10.1016/j.cemconres.2014.07.005
  15. Myers, R.J., Lothenbach, B., Bernal, S.A., Provis, J.L. (2015). Thermodynamic modelling of alkali-activated slag cements, Applied Geochemistry, 61, 233-247. https://doi.org/10.1016/j.apgeochem.2015.06.006
  16. Nguyen, T.T., Waldmann, D., Bui, T.Q. (2019). Computational chemo-thermo-mechanical coupling phase-field model for complex fracture induced by early-age shrinkage and hydration heat in cement-based materials, Computer Methods in Applied Mechanics and Engineering, 348, 1-28. https://doi.org/10.1016/j.cma.2019.01.012
  17. Park, S., Abate, S.Y., Kim, H.K. (2020b). Hydration kinetics modeling of sodium silicate-activated slag: a comparative study, Construction and Building Materials, 242, 118144. https://doi.org/10.1016/j.conbuildmat.2020.118144
  18. Park, S., Abete, S.Y., Lee, H.K., Kim, H.K. (2020a). On the quantification of degrees of reaction and hydration of sodium silicate-activated slag cements, Materials and Structures, 53, 65. https://doi.org/10.1617/s11527-020-01505-9
  19. Provis, J.L., Bernal, S.A. (2014). Geopolymers and related alkali-activated materials, Annual Review of Materials Research, 44, 299-327. https://doi.org/10.1146/annurev-matsci-070813-113515
  20. Provis, J.L., Palomo, A., Shi, C. (2015). Advances in understanding alkali-activated materials, Cement and Concrete Research, 78, 110-125. https://doi.org/10.1016/j.cemconres.2015.04.013
  21. Richardson, I.G., Brough, A.R., Groves, G.W., Dobson, C.M. (1994). The characterization of hardened alkali-activated blast-furnace slag pastes and the nature of the calcium silicate hydrate(CSH) phase, Cement and Concrete Research, 24(5), 813-829. https://doi.org/10.1016/0008-8846(94)90002-7
  22. Thomas, J.J., Allen, A.J., Jennings, H.M. (2012). Density and water content of nanoscale solid C-S-H formed in alkali-activated slag(AAS) paste and implications for chemical shrinkage, Cement and Concrete Research, 42(2), 377-383. https://doi.org/10.1016/j.cemconres.2011.11.003
  23. van Deventer, J.S., San Nicolas, R., Ismail, I., Bernal, S.A., Brice, D.G., Provis, J.L. (2015). Microstructure and durability of alkali-activated materials as key parameters for standardization, Journal of Sustainable Cement-Based Materials, 4(2), 116-128. https://doi.org/10.1080/21650373.2014.979265