Geopolymer concrete/mortar is the new development in the field of building constructions in which cement is totally replaced by pozzolanic material like fly ash and activated by alkaline solution. This paper presented the effect of concentration of sodium hydroxide, temperature, and duration of oven heating on compressive strength of fly ash-based geopolymer mortar. Sodium silicate solution containing Na2O of 16.45%, SiO2 of 34.35%, and H2O of 49.20% and sodium hydroxide solution of 2.91, 5.60, 8.10, 11.01, 13.11, and 15.08. Moles concentrations were used as alkaline activators. Geopolymer mortar mixes were prepared by considering solution-to-fly ash ratio of 0.35, 0.40, and 0.45. The temperature of oven curing was maintained at 40, 60, 90, and 120°C each for a heating period of 24 hours and tested for compressive strength at the age of 3 days as test period after specified degree of heating. Test results show that the workability and compressive strength both increase with increase in concentration of sodium hydroxide solution for all solution-to-fly ash ratios. Degree of heating also plays vital role in accelerating the strength; however there is no large change in compressive strength beyond test period of three days after specified period of oven heating. 1. Introduction Cement industry is one of the major contributors to the emission of green house gasses like carbon dioxide which is about 1.35 billion tons annually [1, 2]. Day by day the World’s Portland cement production increases with the increasing demand of construction industry which crossed one thousand million tons per year. On the other side, fly ash is the waste material of coal based thermal power plant, which is available abundantly but creates disposal problem. Several hectors of valuable land is required for their disposal. As fly ash is light in weight and easily flies, this creates severe health problems like asthma, bronchitis, and so forth. According to the survey, the total fly ash production in the world is about 780 million tons per year [3]. With silicon and aluminum as the main constituents, fly ash is an effective cement replacing material but the utilization is only 17–25%. At present, fly ash is used in the production of Portland Pozzolana Cement, partial replacement of cement and workability improving admixture in concrete, and also in the production of cellular blocks and bricks and in soil stabilization [4]. For every ton of fly ash used in place of Portland cement saves about a ton of carbon dioxide emission to the atmosphere [3]. The mortar and concrete made with fly
References
[1]
J. Davidovits, “Global warming impact on the cement and aggregate industries,” World Resource Review, vol. 6, no. 2, pp. 263–278, 1994.
[2]
D. Hardjito, S. E. Wallah, D. M. J. Sumjouw, and B. V. Rangan, “Geopolymer concrete: turn waste into environmentally friendly concrete,” in Proceedings of the International Conference on Recent Trends in Concrete Technology and Structures (INCONTEST '03), pp. 129–140, Coimbatore, India, 2003.
[3]
D. Hardjito, S. E. Wallah, D. M. J. Sumjouw, and B. V. Rangan, “Properties of geopolymer concrete with fly ash as source material: effect of mixture composition,” in Proceedings of the 7th CANMET/ACI International Conference on Recent Advances in Concrete Technology, pp. 26–29, Las Vegas, Nev, USA, 2004.
[4]
V. Kumar, M. Mathur, S. S. Sinha, and S. Dhatrak, “Fly Ash: an environmental savior,” in Fly Ash Utilisation Programme (FAUP), TIFAC, DST, pp. IV1.1–IV1.4, Fly Ash India, New Delhi, India, 2005.
[5]
V. M. Malhotra and A. A. Ramezanianpour, Fly Ash in Concrete, Canada Centre for Mineral and Energy Technology (CANMET), 1994.
[6]
J. Davidovits, “Geopolymers: man-made geosynthesis and the resulting development of very early high strength cement,” Journal of Materials Education, vol. 16, no. 2-3, pp. 91–139, 1994.
[7]
J. Davidovits, “Geopolymers—inorganic polymeric new materials,” Journal of Thermal Analysis, vol. 37, no. 8, pp. 1633–1656, 1991.
[8]
J. Davidovits, “Recent progresses in concretes for nuclear waste and uranium waste containment,” Concrete International Journal, vol. 16, no. 12, pp. 53–58, 1994.
[9]
A. K. Rai, B. Paul, and G. Singh, “A study on the environmental aspects of coal ash disposal,” Indian Journal of Environmental Protection, vol. 30, no. 12, pp. 1025–1029, 2010.
[10]
V. C. Pandey, J. S. Singh, R. P. Singh, N. Singh, and M. Yunus, “Arsenic hazards in coal fly ash and its fate in Indian scenario,” Resources, Conservation and Recycling, vol. 55, no. 9-10, pp. 819–835, 2011.
[11]
N. P. Rajamane and D. Sabitha, “Effect of fly ash and silica fume on alkalinity of cement mortars,” The Indian Concrete Journal, vol. 79, no. 3, pp. 43–48, 2005.
[12]
S. B. Suri, “Fly ash based innovative building products for construction—part-II,” CE & CR, vol. 25, pp. 134–142, 2012.
[13]
A. M. F. Jiminez, E. E. Lachowski, A. Palomo, and D. E. Macphee, “Microstructural characterisation of alkali-activated PFA matrices for waste immobilisation,” Cement and Concrete Composites, vol. 26, no. 8, pp. 1001–1006, 2004.
[14]
J. Davidovits, “Geopolymer chemistry and properties,” in Proceedings of the 1st European Conference on Soft Mineralurgy (Geopolymere '88), pp. 25–48, Compiegne, France, 1988.
[15]
D. Hardjito, S. E. Wallah, D. M. J. Sumjouw, and B. V. Rangan, “Brief review of geopolymer concrete,” Invited Paper, George Hoff Symposium, American Concrete Institute, Los Vegas, Nev, USA, 2004.
[16]
J. Fongjan and L. Ludger, “Effect of high silica content materials on fly ash-based geopolymeric cement materials,” in Proceedings of the Geopolymer 2005 World Congress: Green Chemistry and Sustainable Development Solutions, pp. 107–111, 2005.
[17]
B. V. Rangan, D. Hardjito, S. E. Wallah, and D. M. J. Sumajouw, “Studies on fly ash-based geopolymer concrete,” in Proceedings of the Geopolymer 2005 World Congress: Green Chemistry and Sustainable Development Solutions, pp. 133–137, 2005.
[18]
D. Hardjito, S. E. Wallah, D. M. J. Sumjouw, and B. V. Rangan, “Effect of mixing time and rest period on the engineering of fly ash-based geopolymer concrete,” in Proceedings of the Geopolymer 2005 World Congress: Green Chemistry and Sustainable Development Solutions, pp. 145–147, 2005.
[19]
D. M. J. Sumajouw, D. Hardjito, S. E. Wallah, and B. V. Rangan, “Fly ash-based geopolymer concrete: an application for structural members,” in Proceedings of the Geopolymer 2005 World Congress: Green Chemistry and Sustainable Development Solutions, pp. 149–152, 2005.
[20]
V. F. F. Barbosa, K. J. D. MacKenzie, and C. Thaumaturgo, “Synthesis and characterisation of materials based on inorganic polymers of alumina and silica: sodium polysialate polymers,” International Journal of Inorganic Materials, vol. 2, no. 4, pp. 309–317, 2000.
[21]
J. G. S. van Jaarsveld, J. S. J. van Deventer, and G. C. Lukey, “The effect of composition and temperature on the properties of fly ash- and kaolinite-based geopolymers,” Chemical Engineering Journal, vol. 89, no. 1–3, pp. 63–73, 2002.
[22]
A. Palomo and A. Fernandez-Jimenez, “Alkaline activation of fly ashes: manufacture of concrete not containing Portland cement,” in Proceedings of the International Conference in Institute Eduardo Torroja (CSIC '99), pp. 1–8, Madrid, Spain, 1999.
[23]
R. V. Ranganath and S. Mohammed, “Some optimal values in geopolymer concrete incorporating fly ash,” The Indian Concrete Journal, vol. 82, no. 10, pp. 26–34, 2008.
[24]
B. M. Mustafa Al Bakri, H. Mohammed, H. Kamarudin, I. K. Niza, and Y. Zarina, “Review on fly ash based geopolymer concrete without Portland cement,” Journal of Engineering and Technology Research, vol. 3, no. 1, pp. 1–4, 2011.
[25]
S. S. Jamkar, Y. M. Ghugal, and S. V. Patankar, “Effect of fineness of fly ash on flow and compressive strength of geopolymer concrete,” Indian Concrete Journal, vol. 87, no. 4, pp. 57–61, 2013.
[26]
S. V. Patankar, S. S. Jamkar, and Y. M. Ghugal, “Effect of sodium hydroxide on flow and strength of fly ash based geopolymer mortar,” Journal of Structural Engineering, vol. 39, no. 1, pp. 7–12, 2012.
