Effects Of Preparation Parameters And Microstructure Of Fly Ash-based Geopolymer On Its Mechanical Properties

Geopolymers are a new class of materials which have advantages of high mechanical properties,environmental protection,low power consumption,etc.Geopolymers are highly significant commercial products and widely used in some areas.Fly ash is a kind of industrial waste leading to serious environmental pollution.Fly ash-based geopolymer is a new type of fly ash utilization approach.In this paper,Fly ash-based geopolymer is suces-sfully prepared.All the fly ash-based geopolymers are characterized using SEM and XRD microscopic analysis technology,discussing the effects of microstructure on mechanical properties and geopolymerization mechanism.It provides a useful way of comprehensive utilization of the mine tailings and other industrial wastes for making geopolymers of more excellent properties.The fly ash comes from the second thermoelectric plant of zibo,and the average particle size is 43.69?m.The total content of main chemical composition of SiO2 and Al2O3 is 82.4%,The content of CaO is 2.52%.After the peak fitting,amorphous phases account for 65.8%of the total quality of the whole materials.Fly ash-based geopolymer is synthesized by alkaline solution activation of fly ash at different curing temperature and time.The effect of NaOH solution,curing temperature,curing time and radio of m(NaOH):m(Na2SiO3)on compressive strength of fly ash-based geopolymer is discussed.Increasing NaOH solution,radio of m(NaOH):m(Na2SiO3)and curing temperature contribute to the development of compressive strength of fly ash-based Geopolymer.The optimal parameter of 50?and 65 ? is 14d,The optimal parameter of 80? is 3d.The low module(0.94-1)of Na2SiO3 solution has no impact on the development of compressive strength of fly ash-based Geopolymer.Parameter on the opitum compressive strength 18.57MPa is 80?,3d,m(NaOH):m(Na2SiO3)? 3:2.3D microscope?XRD and SEM analysis show that all products had geopolymeriza-tion to some extent on different technolygical conditions and the geopolymeric gels are enveloped by the unreacted particles.Having no new crystalline phases indicates the crystalline phases don't participate in the geopolymerization,maybe amophous phases.the geopolymeric gels are similar to the crystalline phases of analcite.The development degree and the space distribution of the geopolymeric gels are the main factors influencing the mechanical properties.Zeolite diffraction peaks is obsetved in the low angle 5° with the increase of NaOH solution or curing temperature.Geopolymerization system is given priority to geopolymeric gels and maybe accompanied by the formation of tiny crystalline phases.The tiny crystalline phases and unreacted particles support the geopolymeric gels,enhancing the mechanical properties.