Production Geopolymer Materials by Coal Fly Ash

Abstract : Coal ash is the main waste from power plant. It is estimated that the consumption of the coal for power plant will increase to 240 million tons each year and the coal ash wastes will produce more than 2 million tons per year. Although the utilization of coal fly ash can be reached 74.1%, large amount of coal fly ash and bottom ash still cannot be utilized. The purpose of this research is to develop a process to manufacture geopolymer using coal fly ash waste. The test results show that the characteristics of waste coal fly ash-based geopolymer have great physical/mechanical properties for fire resistance test. A 10 mm thick geopolymer panel was exposed to a 1100¢J flame, with the measured back-side temperatures reaching less than 470¢J after 30 minutes. The products can be fabricated for construction purposes and have great application potential. Keyword: coal fly ash, geopolymer, fire resistances

Introduction
Throughout the world, the amount of coal fly ash from power plant is increasing. The production of coal fly ash from Tai-Power Company (TPC) is about two million tons per year and the quantity of fly ash is four times of bottom ash in Taiwan (Kuo, 1991 Kuo, 1994 ¡F ¡FLee et al., 1998¡FWang et al., 1996). For the purpose of energy, economic developing, and environmental ecosystem conserving, many research works and development investigations have been conducted in its utilizations as a starting material, such as using coal fly ash to produce artificial reef (Kuo, 1994), as an addition materials for concrete (Kuo, 1994; Lai, 1994¡FYang, 1997), raw materials of ceramic (Wang et al., 1994), etc. The reuse amount of fly ash is still limited. However, due to the coal fly ash in Taiwan is classified as Class F (Yen, 1996), and it could be a good raw material for making geopolymer. Geopolymers, an inorganic polymer, firstly developed by Joseph Davidovits in 1978 (Comrie and Davidovits, 1988; Davidovits et al., 1990), have been gradually attracting

References: [1] Comrie, D. C. and Davidovits, J., “Long term durability of hazardous toxic and nuclear waste disposals”, Geopolymer ’88, First European Conference on Soft Mineralurgy. Compiegne, France, pp. 125-134, [1988] [2] Davidovits, J., Comrie, D. C., Paterson, J. H. and Ritcey, D. J., “Geopolymeric concretes for environmental protection”, Concrete International, pp. 30-40, [1990] [3] Davidovits, 1999a, “Chemistry of geopolymeric systems terminology”, Proceeding of Geopolymer’99 Second International Conference, Editors: Davidovitis, J., Davidovits, R. and James, C., France, pp. 9-37. [4] Davidovits, J., 1999b, “Fireproof geopolymeric cements”, Proceeding of Geopolymer’’99 Second International Conference, Editors: Davidovites, J., R. and James, C., France, pp. 165-169. [5] Hua, X., and Van Deventer J.S.J., 1999, “The geopolymerisation of natural alumino-silicates”, In: Proc. 2nd Internat. Cof. Geopolymere ’99, pp.43-63. [6] Ke, Y. C., “Fire-proof materials”, Ceramic Technology Handbook, Editor: J. M. Wang, Hsinchu, pp.1045-1110, [1994] (in Chinese) [7] Kuo, S. T., “Utilization of fly ash”, Mining Technology, Vol. 29, No. 4, pp. 299-315, [1991] (in Chinese) [8] Kuo, S. T., “A Review on the Research Experience of Coal Ash Artificial Reef in Taiwan”, Taipower engineering, No. 547, pp.22-31, [1994] (in Chinese) [9] Lai, C. I.,“Characteristics of High Volume Fly Ash Concrete”, Taipower engineering, No. 551, pp. 60-70, [1994] (in Chinese) [10] Lee, C. H., S. T. Kuo, “An Investigation of the Properties of Coal Bottom Ash from TPC”, Taipower engineering, No. 551, pp. 56-71, [1998] (in Chinese) [11] Swanepoel, J.C., C.A. Strydom, “Utilisation of fly ash in a geopolymeric material”, Applied Geochemistry 17, pp. 1143-1148, [2002] [12]Wang, C. H., S. T. Kuo, “Utilization of Fly-Ash Ceramic Made from Fly Ash”, Ceramics, Vol.15, No.1, pp 36-44, [1996] (in Chinese) [13] Wang, M. L., K. W. Peng and S. B. Wen, “The study of treating fly ash as raw material of ceramic”, Proc. 9th Conf. On Waste Management Technology in Republic of China, Nov, pp.403-412, [1994] (in Chinese) [14]Xu, H., Van Deventer, J.S.J., Lukey, G.C., “Effect of alkai metals on the preferential geoplymeriazation of stilbite/kaolinite mixtures”, Int. Eng. Chem. Res. 40, pp3749-3756, [2001] [15]Yang, K. I., “Utilization of Granulated Blast-Furnace Slag in Cement and Concrete”, Technology and Training, Vol. 22, Vol. 22, No. 3, pp 118-132, [1997] (in Chinese) [16]Yen, Tsong, “The engineering properties of fly ash concrete”, Utilization fly ash to promote the quality of concrete, Editor: M. J. Lee, pp.105-150, [1996] (in Chinese) - 266 -