Evaluation of Optimum Mix Proportion and Strength of Volcanic Ash based Geopolymer

화산재 기반 지오폴리머의 최적배합 도출 및 강도 특성

  • Nam, Chang-Sik (Department of Civil Engineering, University of Seoul)
  • 남창식 (서울시립대학교 토목공학과)
  • Received : 2017.04.21
  • Accepted : 2017.06.09
  • Published : 2017.06.30


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.


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


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