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2025-01-24 14:35本頁面
【正文】 and the mechanism of activation of reactivity of CFB ashes and its expansion are investigated by XRD and SEM. Finally, the utilization in building materials of CFB ashes is studied.The results show that: (1) The CFB ashes is different from the ashes of mon coal boiler for there are great difference in forming condictions such as the bustion temperature, bustion environment, the degree of bustion, desulfurizer and the efficiency of desulfurization. While CFB ashes have the properties of cement and expansion for its containing SO3 and fCaO, so it is a special pozzolanic material. (2) The SO3 and fCaO have their properties for their typical forming condition. SO3 is fixed in ashes at 850~900℃, and it exists in ⅡCaSO4 and has different solubility with the natural anhydrite and the plaster calcined at 400℃. It is the first time to prove that the particles of fCaO is coated withⅡCaSO4 by investigating the process of forming fCaO, the microstructure, spathic type and optic parameter and the hydrating process. Results also show that the microstructure can slow down the hydrating and deteriorate the reactivity of CFB ashes. (3) The current method evaluating reactivity of pozzolanic materials has great limits to evaluate the CFB ashes. A series of new methods are developed which can evaluate the reactivity and its devotion to strength really and directly. (4) The reactivity of CFB ashes is attributed to the amorphous SiO2 and Al2O3, but the SO3 and fCaO of CFB ashes can influence its reactivity and expansion, and there is an optimum content. The higher reactivity can be achieved if the fineness is bigger. (5) The mon method can activate its reactivity, but the result of activation is not ideal in the point of strength. It shows that steam curing and highpressure steam curing is best to activate CFB ashes, especially for highpressure steam curing. (6) The expansion mechanism of CFB ashes is the expansion of the forming of ettringite and the solution and crystallization of ⅡCaSO4. (7) Fineness is beneficial to stabil
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