Characteristics And Application Of Fluidized Bed Combustion Fly Ashes In Cementious Self-leveling Mortar

CFBC fly ashes and slags are wastes of circulating fluidized bed combustion（CFBC）boiler. It contain some contents of f-CaO and Ⅱ-CaSO4, which will bring onself-harding and expansion after hydration. For this reason, CFBC ashes and slags couldnot be directly used as building materials because of cracking. In present, the utilizationratio of CFBC fly ashes and slags was less than50%, and CFBC fly ash which wasabout50%of total fly ashes and slags were accumulation disposal. The utilization ofCFBC fly ashes has become the foucs in area of CFBC.As we known, expansion components and high performance cementitiousmaterials were necessary in self-leveling mortar (CSLM). Based on the characteristicsof CSLM and CFBC fly ashes, the using of CFBC fly ash as expansive agent and partialcementitious material was studied in process of CSLM with low shrinkage and highstrength. In this dissertation, the characteristics of CFBC fly ash were tested. And theinfluence of fineness and contents of CFBC on the performance of the CSLM was alsostudied. Finally, the effect of the addition of mineral admixture and other additives inCSLM was studied.Results showed that: the water requirement of normal consistency decreased withfineness of CFBC fly ash in certain range, meanwhile, the hydration exothermic rateincreased with fineness. The hydrated expansive product of CFBC fly ash and CFBC flyash with cement were gypsum and ettringite. And great expansion was obtained in eralystage, with fineness of CFBC fly ash, while the expansion of the paste would be stablein later stage. Greater expansion was obtained with increasing of fineness and content ofCFBC fly ash in cement-CFBC fly ash paste.Application of CFBC fly ash in CSLM showed that: high strength and lowshrinkage could be obtained when CFBC fly ash was used to replace cementiousmaterial and anhydrite. The fludity and compactness would be influenced by proportionof fine aggregate in CSLM. The optimium fludity and strength could be obtained bydesign the proper mixture ratio. Besides, high early and late stage strength could beobtained when appropriate proportion of cement-sand ratio and high alumina cementwas applied in CSLM. When cement was partially replaced by CFBC fly ash within acertain range, the strength of the mortar increased with the fineness of CFBC fly ash. As the content of CFBC fly ash increased from0%to60%, the shrinkage of the mortardecreased while the strength of the mortar first increased and then decreased. Theshrinkage decreased with increasing of CFBC fly ash content. When other mineraladmixtures were added, the addition of phosphorus slag powder in the mortar couldimprove the strength of the mortar and reduce the shrinkage.The>9MPa of28d flexural strength,>35MPa of compressive strength and<0.029%of shrinkage could be obtained with the addition of CFBC fly ash in CSLM.Resource utilizition approach of CFBC fly ash can be obtained meanwhile expasiveagent and cementious material were provided for CSLM in this research.