Fly Ash - Metakaolinite Base Of Mineral Polymer Synthesis And Polymerization Reaction Mechanism

The stockpile of tailings and industrial solid waste fly ash not only take up a lot of land,but also threaten entironment and ecological balance in some extent.Aim at the phenomenon,the utilization of tungsten tailings and fly ash is explored in this study.The aim of sustainable development of resource. The fly ash-metakaolin based geopolymer is synthesized at normal temperature in this study,with replace part metakaolin by fly ash and the alkali activator compose of sodium silicate solution and alkali solution. A orthogonal with four factors and four levels is designed.The order of the main impact factors is: NaOH solution concentration> solid to liquid ratio>the content of water glass in the liquid phase> fly ash content by intuitionistic and range analysis.The optimum condition of geopolymer is gained by validate experiment.When the content of fly ash is 30%,the concentration of NaOH is 12M,solid to liquid ratio is 4.5,the content of water glass in the liquid phase is 65%.Infrared analysis shows that the rule Si-O and Al-O structure of the raw material has been generated Si-O- Al polymer structure by reaction.X-ray difftaction shows that the structure of the aluminum silicate gel present amorphous to semi-crystalline state.For different solid-liquid ratio,IR show that the polymerization is vary.XRD show that the content of aluminosilicate gel is different.When the aggregate isn't mix,the optimal solid-liquid ratio of pure metakaolin geopolymer is 1.1, the optimal solid to liquid ratio of pure fly ash geopolymer is 2.75, the optimal solid to liquid ratio of fly ash-metakaolin geopolymer is 1.7.At the basis of solid-liquid ratio,the impact mechanism of the fly ash content is explored. Infrared and X-ray difftaction show that the whole hydrous process is slow.And a small a little amorphous gel phase is generated.SEM show that most of the material is not involved in the reaction.It's disadvantage for the development of the strength.As the pure fly ash geopolymer, Infrared analysis and X-ray difftaction show that the few with the gel,the slowly with the development of the strength.SEM show that the structure of the network is dense.For the fly ash-metakaolin based geopolymer, Infrared and X-ray difftaction show that the hydration reaction is quickly.A lot of amorphous gel are generated in the early stage.When the content of fly ash is 20% and 30%, in the whole curing age,the solid material particles are excited thoroughly.The amount of the amorphous gel are the most. When the content of fly ash is 30% ,SEM shows that the structure of the aluminum silicate gel is continous.The dispersion degree is small.The structure is compaction.Thereby increasing the strength of the geopolymer. When the content of fly ash is 50% ,SEM shows that the more content of fly ash slow the hydtation reaction.The base of the production is crisp,and the microcrack is formed.Than the overall performance of the geopolymer is reduced.The end result is that fly ash and metakaolin exist synergistic effect and promote polymerization of geopolymers together.