# 화산재 기반 지오폴리머의 최적배합 도출 및 강도 특성

• Nam, Chang-Sik (Department of Civil Engineering, University of Seoul)
• 남창식 (서울시립대학교 토목공학과)
• Accepted : 2017.06.09
• Published : 2017.06.30
• 45 2

#### Abstract

This study determined the optimum mix proportions for volcanic-ash-based geopolymer by analyzing the flow, setting time, and compressive strength. $Na2SiO_3$ and NaOH were used as alkali activators, and NaOH concentrations of 2, 4, 6, and 8M were used for different experimental cases. The A/B ratios examined were 0.25, 0.3, 0.35, 0.4, and 0.45, and the ratios of volcanic ash to blast furnace slag binder were 7:3, 6:4, and 5:5. In the experiment, the flow and setting time tended to decrease and the compressive strength increased as the molarity of NaOH in the geopolymer increased. The optimum molarity of NaOH was determined to be 4M. As the A/B ratio increased, the setting time decreased and the compressive strength increased. The most advantageous A/B ratio for the setting time and strength was 0.35. Increasing the ratio of volcanic ash resulted in a longer setting time and lower compressive strength. The optimum binder ratio was chosen as 6:4 based on the setting time and compressive strength. Thus, 4M of NaOH, an A/B ratio of 0.35, and binder ratio of 6:4 are considered as the proper parameters for the volcanic-ash-based geopolymer.

#### Keywords

A/B Ratio;Binder Ratio;Blast Furnace Slag;Geopolymer;NaOH;Volcanic Ash

#### References

1. Korea Institute of Civil Engineering and Building Technology, "A Study on the Performance Improvement of Concrete using Admixture", Korea Institute of Civil Engineering and Building Technology A Research Report, 2008.
2. F. Q. Zhao, W. Ni, H. J. Wang, H. J. Liu, "Activated fly ash/slag blended cement", Conservation and Recycling, vol. 52, no. 2, pp. 303-313, 2007. DOI: https://doi.org/10.1016/j.resconrec.2007.04.002 https://doi.org/10.1016/j.resconrec.2007.04.002
3. T. Bakharev, "Geopolymeric materials prepared using Class F fly ash and elevated temperature curing", Cement and Concrete Research, vol. 35, pp. 1224-1232, 2005. DOI: https://doi.org/10.1016/j.cemconres.2004.06.031 https://doi.org/10.1016/j.cemconres.2004.06.031
4. S. T. Kang, G. S. Ryu, K. T. Koh, J. H. Lee, "Optimum Mix Design of Alkali-Activated Cement Mortar using Bottom Ash as Binder", Journal of the Korea Concrete Institute, vol. 23, no. 4, pp. 487-494, 2011. DOI: https://doi.org/10.4334/JKCI.2011.23.4.487 https://doi.org/10.4334/JKCI.2011.23.4.487
5. M. Palacios, F. Puertas, "Effect of shrinkage reducing admixtures on the properties of alkali-activated slag mortars and pastes", Cement and Concrete Research, vol. 37, no. 5, pp. 691-702, 2007. DOI: https://doi.org/10.1016/j.cemconres.2006.11.021 https://doi.org/10.1016/j.cemconres.2006.11.021
6. J. Davidovits, "Geopolymers and geopolymeric materials", Thermal Analysis and Calorimetry, vol. 35, no 2, pp. 429-441, 1989. DOI: https://doi.org/10.1007/BF01904446 https://doi.org/10.1007/BF01904446
7. M. Sofi, Van. Deventer, P. A. Mendis, G. G. Lukey, "Engineering Properties of Inorganic Polymer Concretes (IPCs)", Cement and Concrete Research, vol. 37, no. 2, pp. 251-257, 2007. DOI: https://doi.org/10.1016/j.cemconres.2006.10.008 https://doi.org/10.1016/j.cemconres.2006.10.008
8. D. Bondar, C. J. Lynsdale, N. B. Milestone, N. Hassani, A. A. Ramezanianpour, "Effect of type, form, and dosage of activators on strength of alkali-activated natural pozzolans", Cement and Concrete Composites, vol. 33, no. 2, pp. 251-260, 2011. DOI: https://doi.org/10.1016/j.cemconcomp.2010.10.021 https://doi.org/10.1016/j.cemconcomp.2010.10.021
9. E. Garcia, K. Campos-Venegas, A. Gorokhovsky,A. Fernandez, "Cementitious composites of pulverized fuel ash and blast furnace slag activated by sodium silicate: effect of $Na_2O$ concentration and modulus", Advances in Applied Ceramics, vol. 105, no. 4, pp. 201-208, 2006. DOI: https://doi.org/10.1179/174367606X120151 https://doi.org/10.1179/174367606X120151