Optimising High Lime Fly Ash Content By Means of Silica Fume İncorporation To Control Alkali-Silica Reaction And Drying Shrinkage of Mortars

In this study, the effect of binary and ternary cementitious systems composed of portland cement, high-lime fly ash and silica fume on the compressive strength, alkali-silica reaction (ASTM C 1567) and drying shrinkage of mortar mixtures was researched. For this purpose, binary and ternary binders were prepared with partial replacement of cement with either fly ash (15wt% and 30wt%) or silica fume (5wt%) or both mineral admixtures (15wt+%5wt% and 30wt%+5wt%). An alkali reactive basalt aggregate was used in this study. It was found that partial replacement of cement with high-lime fly ash reduced the strength of mortar mixtures even up to 28-days. Besides, addition of 5% silica fume had not a significant effect on the early strength of fly ash-bearing mixtures. However, silica fume inclusion improved the 28-day strength of mixtures. In terms of alkali-silica reaction (ASR), the fly ash with lower lime content reduced the 14-day expansion more than that of fly ash with higher lime content. The opposite results were the case in 28-day ASR expansions. The ASR expansions of the fly ash-bearing mixtures were significantly reduced by the introduction of the additional 5% silica fume to these mixtures. However, silica fume incorporation remarkably increased the drying shrinkage values of the mixtures. Finally, fly ash with higher lime content was found to be more satisfactory in terms of compressive strength, alkali-silica reaction and drying shrinkage in the ternary binder system.

Optimising High Lime Fly Ash Content By Means of Silica Fume İncorporation To Control Alkali-Silica Reaction And Drying Shrinkage of Mortars

In this study, the effect of binary and ternary cementitious systems composed of portland cement, high-lime fly ash and silica fume on the compressive strength, alkali-silica reaction (ASTM C 1567) and drying shrinkage of mortar mixtures was researched. For this purpose, binary and ternary binders were prepared with partial replacement of cement with either fly ash (15wt% and 30wt%) or silica fume (5wt%) or both mineral admixtures (15wt+%5wt% and 30wt%+5wt%). An alkali reactive basalt aggregate was used in this study. It was found that partial replacement of cement with high-lime fly ash reduced the strength of mortar mixtures even up to 28-days. Besides, addition of 5% silica fume had not a significant effect on the early strength of fly ash-bearing mixtures. However, silica fume inclusion improved the 28-day strength of mixtures. In terms of alkali-silica reaction (ASR), the fly ash with lower lime content reduced the 14-day expansion more than that of fly ash with higher lime content. The opposite results were the case in 28-day ASR expansions. The ASR expansions of the fly ash-bearing mixtures were significantly reduced by the introduction of the additional 5% silica fume to these mixtures. However, silica fume incorporation remarkably increased the drying shrinkage values of the mixtures. Finally, fly ash with higher lime content was found to be more satisfactory in terms of compressive strength, alkali-silica reaction and drying shrinkage in the ternary binder system.

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  • 1. Thomas M. D. A., Shehata M. H., Shashiprakash S. G., Hopkins D. S. and Cail K., “Use of ternary cementitious systems containing silica fume and fly ash in concrete”, Cement and Concrete Research, 29: 1207-1214, (1999).
  • 2. Lam L., Wong Y. L. and Poon C. S., “Degree of hydration and gel/space ratio of high-volume fly ash/cement systems”, Cement and Concrete Research, 30: 747-756, (2000).
  • 3. Zhang Y. M., Sun W. and Yan H. D., “Hydration of high-volume fly ash cement pastes”, Cement and Concrete Composites, 22: 445-452, (2000).
  • 4. Yazıcı H., Aydın S., Yiğiter H. and Baradan B., “Effect of steam curing on class C high-volume fly ash concrete mixtures”, Cement and Concrete Research, 35: 1122-1127, (2005).
  • 5. Hemalatha T. and Sasmal S., “Early-age strength development in fly ash blended cement composites: Investigation through chemical activation”, Magazine of Concrete Research, (Ahead of Print), (2018).
  • 6. Mehta P. K. and Monteiro P. J. M., “Concrete: Microstructure, properties, and materials", Third edition, McGraw-Hill, (2006).
  • 7. Malhotra V. M. and Carette G. G., “Silica fume concrete-properties, applications and limitations”, Concrete International: Design and Construction, 5: 40-46, (1983).
  • 8. Bickely J. A., Ryell J., Rogers C. and Hooton R. D., “Some characteristic of high strength concrete”, Canadian Journal of Civil Engineering, 18: 885-889, (1991).
  • 9. Temiz H. ve Yeğinobalı A., “Uçucu kül ve silis dumanı katkılı çimento hamur ve harçlarının bazı özellikleri”, Endüstriyel Atıkların İnşaat Sektöründe Kullanılması Sempozyumu, İMO, Ankara, 213-226, (1995).
  • 10. Bagheri A. R., Zanganeh H. and Moalemi M. M., “Mechanical and durability properties of ternary concretes containing silica fume and low reactivity blast furnace slag”, Cement and Concrete Composites, 34: 663-670, (2012).
  • 11. Khayat K. H. and Aitcin P. C. “Silica fume in concrete: an overview”, ACI SP-132, Detroit, 835-865, (1992).
  • 12. Thomas M. D. A., Shehata M. H. and Shashiprakash S. G., “The use of fly ash in concrete: classification by composition”, Cement, Concrete, and Aggregates, 21: 105-110, (1999).
  • 13. ASTM C 1567, “Standard test method for determining the potential alkali-silica reactivity of combinations of cementitious materials and aggregate (Accelerated mortar-bar method)”, ASTM, USA, (2013).
  • 14. ACI Committee 232, “Use of Fly Ash in Concrete”, ACI, Detroit, (1996).
  • 15. Roy D. M., Luke K. and Diamond S., “Characterization of fly ash and its reactions in concrete”, MRS Symposium Proceedings, Materials Research Society, Pittsburgh, 43: 3-20, (1985).
  • 16. Hemmings R. T. and Berry E. E., “On the Glass in Coal Fly Ashes: Recent Advances”, MRS Symposium Proceedings, Materials Research Society, Pittsburgh, 113: 3-38, (1988).
  • 17. Mehta P. K., “Pozzolanic and cementitious by-products—Another look”, Proceedings of the Third International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, ACI SP-114, Detroit, 1–43, (1989).
  • 18. Mehta P. K., “Influence of fly ash characteristics on the strength of portland-fly ash mixtures”, Cement and Concrete Research, 15: 669-674, (1985).
  • 19. Shehata M. H. and Thomas M. D. A., “Use of ternary blends containing silica fume and fly ash to suppress expansion due to alkali–silica reaction in concrete, Cement and Concrete Research, 32: 341-349, (2002).
  • 20. Thomas M., “The effect of supplementary cementing materials on alkali-silica reaction: A review”, Cement and Concrete Research, 41: 1224-1231, (2011).
  • 21. Rajabipour F., Giannini E., Dunant C., Ideker J. H. and Thomas M. D. A., “Alkali–silica reaction: Current understanding of the reaction mechanisms and the knowledge gaps”, Cement and Concrete Research, 76: 130-146, (2015).
  • 22. Nath P. and Sarker P., “Effect of fly ash on the durability properties of high strength concrete”, Procedia Engineering, 14: 1149-1156, (2011).
Politeknik Dergisi-Cover
  • ISSN: 1302-0900
  • Yayın Aralığı: Yılda 4 Sayı
  • Başlangıç: 1998
  • Yayıncı: GAZİ ÜNİVERSİTESİ