| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 96 === This study explores the influences of the following factors on the engineering properties of geopolymer: (1) sintering temperature and time of kaolin, (2) amounts of silicon and aluminum ions released from kaolin, (3) weight ratio of SiO2 to Na2O (SiO2/Na2O), (4) ratio of liquid volume to solid weight (liquid/solid), and (5) raw materials.
Results are summarized as the following: (1) Effective sintering temperature and time was differentiated by thermal analysis and XRD. The dehyrdoxylation of kaolin did not occur until the heating temperature was maintained at 700 °C for 3 hours. (2) When liquid/solid=5, by adding different volumes of the alkali activation of 10 N KOH solutions, the released aluminum ions reached the maximum amounts earlier than the silicon ions. (3) When SiO2/Na2O=0.4, the geopolymer had large heat release and rapid stiffening, inducing poor workability, pores, and thermal cracks. Its engineering properties were thus bad. However, when SiO2/Na2O=0.7 or 1, compressive strength of the geopolymer was optimized by changing the liquid/solid ratios. Therefore, better engineering properties of the geopolymer can be achieved by adjusting both the SiO2/Na2O and liquid/solid in a mix design to get a better bond. (4) Engineering properties of the geopolymer varied with the physical and chemical properties of the kaolin of different origins. Therefore, the concepts of water-cement ratio or water-cementitious materials ratio are not applicable on the geopolymerization. It is suggested that the materials properties of the reactants should be determined and the chemical reactions during the geopolymerization should be clarified prior to the mix design. (5) Geopolymer had high compressive strength and low thermal conductivity, suggesting its potential use on fire-resistance and thermal insulation.
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