Papers by Keyword: Geopolymer

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Authors: Mei Xun Peng, Zheng Hong Wang, Shao Hua Shen
Abstract: Class F fly ash-based geopolymers formed by pressure were prepared, and the preparation factors effecting on properties especially mechanical strength were discussed and optimized. The geopolymer specimens show excellent integrated properties such as mechanical strength, acid-resistance and water absorption and can be potentially applied to acid-resisting bricks except for acid-resistance left to be improved. The elevated curing temperature and the prolonged curing time are both beneficial to develop the mechanical strength as well as the moderately increased forming pressure and quartz sand/fly ash ratio. Being pretreated at elevated temperature for proper time before press forming improves the mechanical strength and reduces the water absorption greatly.
Authors: Wan Mastura Wan Ibrahim, Kamarudin Hussin, Mohd Mustafa Al Bakri Abdullah, Aeslina Abdul Kadir, Mohammed Binhussain
Abstract: This paper offers a review on production of fly ash-based geopolymer bricks.Bricks are the world’s most versatile, durable and reliable construction material.Conventional bricks are produced from clay with high temperature kiln firing or from ordinary Portland cement (OPC) concrete,and thus contain high embodied energy and have large carbon footprint. In many areas of the world,there is already a shortage of natural source material for production of the conventional bricks. For environmentalprotection and sustainable development, extensive research has been conducted on productionof bricks from waste materials.Fly ash is a waste material of coal firing thermal plants and its accumulation near power plants causes severe pollution problems. Therefore, its utilization as a raw material for brick making will be a very beneficial solution in terms of economic and environmental aspects.
Authors: Ikmal Hakem Aziz, Mohd Mustafa Abdullah Al Bakri, Heah Cheng Yong, Liew Yun Ming, Kamarudin Hussin, Emy Aizat Azimi
Abstract: Geopolymer is cementitious binder that has enormous potential to become an alternative to ordinary Portland cement (OPC). Geopolymer composites have the potential to substantially curb the carbon dioxide (CO2) emissions. Kaolin, metakaolin, slag and fly ash have been used as the prime materials for forming geopolymers composites. Geopolymers have been studied for the past decade due to its unique properties such as low shrinkage, substantially chemical resistance, and higher fire resistance. The geopolymer offer an innovative for coating application at higher thermal application. Based on historical review, geopolymer materials exhibit resistance to corrosion, abrasion and heat. This paper summarizes some research finding about alkali-activated binders over the past decades along with outlines of the potential of geopolymer composites for high temperature application.
Authors: Laila Mardiah Deraman, Mohd Mustafa Al Bakri Abdullah, Yun Ming Liew, Kamarudin Hussin, Zarina Yahya
Abstract: Geopolymerization are chemical reaction between raw material and alkaline activator where a rapid change of some partial armorphous, specific structure into a compact cemented framework. It was treated with an alkali silicate solution at 45 – 80 °C whereas it’s formed from reaction of mineral clays or aluminosilicate-bearing industrial waste. The previous study about geopolymer has been done for many years due to the physical and chemical properties which is suitable to use in the construction industry. A Geopolymer material that was containing most Silica (Si) and Aluminium (Al) is such as fly ash, bottom ash, metakaolin and ground granulate blast slag (GGBS). Bottom ash is produced from coal fired thermal power plant and has a physical characteristic similar as sand or gravel sand that makes it ideal for industrial application like a green concrete. The different performance of geopolymer is according to the different content of silica, alumina and calcium. To obtain the best geopolymer material, parameter of raw materials content, the types and ratio of alkaline activators also the curing method will affect the high result of compressive strength. This paper will summarize a previous researchers work about the alkali-activated binder in geopolymer raw materials to become green product.
Authors: Xi Ling Zhang, Ai Ling Yao, Lin Chen
Abstract: Geopolymers Are Attracting Great Interest from Mining and Energy Industries Alike, to Solve their Pressing Waste Disposal Problems. Geopolymers for Immobilization of Heavy Metal Consist of an Alkaline Activator and Cementing Components, such as Metakaolin, Coal Fly Ash, Slag, Etc., or a Combination of Two or More of them. its Main Hydration Product Is Aluminosilicate Gel at Room Temperature. Properly Designed Geopolymers Can Exhibit both Higher Strengths and Lower Leading than Portland Cement. the Exact Mechanism by which Heavy Metal Immobilization Occurs Is Not Fully Understood, and it Is Thought to Be Caused by Three Routes. this Paper Also Analyzes the Existing Problems in the Process on the Immobilization of Heavy Metal with Geopolymers Research, and its Development Is Prospected.
Authors: Muhammad Irfan Khan, Khairun Azizi Azizli, Suriati Sufian, Zakaria Man, Amir Sada Khan, Hafeez Ullah, Ahmer Ali Siyal
Abstract: Infra-red spectroscopic (IR) analysis of the geopolymers provides information regarding gel chemistry, quantitative analysis, kinetics and effect of different activators on geopolymers. This review discusses the IR analysis of geopolymers and their starting materials. Different applications of IR spectroscopy, used in geopolymerization, are explored in detail. Future research questions regarding IR analysis of geopolymers are also discovered
Authors: Z.F. Farhana, H. Kamarudin, Azmi Rahmat, A.M. Mustafa Al Bakri
Abstract: This paper presents a study on the relationship between porosity and compressive strength for geopolymer paste. In this research, geopolymer paste was made from fly ash class F based geopolymer mixed with alkaline activator; sodium hydroxide solution and sodium silicate solution. Twelve mixes were cast in 50mm x 50mm x 50mm moulds and the samples were cured for 24 hrs at 60 °C in the oven. The samples were examined after 7, 14, 28 and 90 days in terms of porosity test, pulse velocity test and compressive strength test. It was concluded that the sample at day 90 had the highest compressive strength of 56.50 N/mm2 had porosity 3.77%. Thus, the sample with lowest porosity had highest pulse velocity 3303 m/s during ultrasonic testing with lowest transmission time 15.17 μs. Keywords: porosity, compression strength, geopolymer, pulse velocity
Authors: Alexandros Tsitouras, Sotirios Tsivilis, Glykeria Kakali
Abstract: There are several factors that affect geopolymerization, including the type and ratios of the starting materials as well as the curing conditions of the initial mixture. The effect of the synthesis parameters on the formation of inorganic polymers are usually examined by “changing one factor at a time”. In this study Taguchi experimental designing model was applied in order to study the synergetic effect of selected synthesis parameters on the compressive strength development of metakaolin based geopolymers. The experimental design involved the variation of three control factors in five levels. The selected factors and the corresponding level range were: i) the alkali to aluminum molar ratio in the starting mixture (0.5-1.5), ii) the kind of alkali ion (Na and/or K) and iii) the molar ratio of Si to alkali oxide in the activation solution (0-2.0). The compressive strength of geopolymers was measured and the final products were also examined by means of XRD, FTIR and SEM. As it is concluded, the optimal synthesis conditions for metakaolin geopolymers are R/Al=0.75, Na/(Na+K)=0.50 and [Si]/R2O=1.50, while the factor having the highest impact on the development of compressive strength is the [Si]/R2O ratio.
Authors: Chang Seon Shon, Dongoun Lee
Abstract: The utilization of fly ashes produced by circulated fluidized bed combustion (CFBC) has been limited in construction application due to their inherent high sulfate and carbon contents although CFBC fly ash exhibits very good binding properties without requiring any supplementary activator. This study reports alkali silica reaction (ASR) behavior of CFBC fly ash geopolymer mortars in terms of activation energy using a modified ASTM C 1260/C 1567. Two different strengths of NaOH solution were used to test reactive and potentially reactive aggregates in the presence of CFBC fly ash. The other variables included a longer test period of 3 months and three different temperatures, namely 60°C, 70°C, and 80°C. It was observed that there was no significant expansion in CFBC fly ash based geopolymer mortar regardless of variation of temperature and alkalinity of test solution. Activation energy of CFBC fly ash geopolymer for ASR was higher than that of plain cement mortar irrespective of strength of NaOH solution.
Authors: Laëticia Vidal, Emmanuel Joussein, Joseph Absi, Sylvie Rossignol
Abstract: Geopolymers are inorganic materials obtained by the alkaline activation of aluminosilicate sources. The ammonium molybdate could be used as a complexant for silica in order to complex the siliceous species in the alkaline solution. According to this, the aim of this work is to control the siliceous species and to understand the role of ammonium molybdate as a complexing agent acting on the formation of the different networks. To do this, additions of ammonium molybdate (up to 0.32% molar) in the silicate solution were realized along the formulation of geopolymer using two metakaolins. The results highlight that the addition of ammonium molybdate in geopolymer results in a decrease of the shrinkage at high temperature. Moreover, X-ray diffraction data and SEM after calcination show that geopolymers without ammonium molybdate form two phases (KAlSi2O6 and KAlSiO4) while with additions of molybdate, there were only the phase KAlSi2O6 associated with Al2O3 doped Mo and K2Mo2O7. Finally, SEM observations show that additions of ammonium molybdate seem to favor crystallization. The results allow to evidence the role of molybdate in the control of the polycondensation reaction in order to influence the formation of specific network
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