| China is an energy consumption country, which keeps growing at8%annu ally since2000year and coal consumption accounted for about70%. Circulating fluidized bed combustion (CFBC) technology is an advanced clean combustion t echnology which has advantages such as low temperature combustion (under850℃-950℃), higher combustion efficiency, lower NOx emissions, higher degree o f desulfurization and stable operation over a large range of load regulation and s o on. However, CFBC fly ash is stacked for its performance, which impedes hea vily the development of CFBC technology. Grouting material as a kind of specia1dry mix mortar has a wide market prospect with its high-added value. Applying CFBC fly ash to grouting material not only has obvious economic benefits, but also has good social benefits.Performance of CFBC fly ash is firstly studied and is applied to grouting material. Influence factors of vertical expansion rate, fluidity and strength of gro uting material are studied through single-factor and orthogonal experiment is use d to research the interaction of all influence factors. Linear expansion of cement with CFBC fly ash is deeply studied and methods of controlling the expansion of CFBC fly ash are also discussed. In order to overcome low activity of CFBC fly ash in early days, effect of exciting agent on fluidity and strength of grouting m aterial is studied. To improve the work performance of grouting material, effect of retarder and slumping agent on rheological property of grouting material are r esearched. Besides, long-term performance of grouting material is tested.Increasing water to binding material ratio, water reducer content, binding material to sand ratio and reducing CFBC fly ash content, fineness and adding th e aluminum paste could improve the fluidity of grouting material. Reducing bind ing material to sand ratio, CFBC fly ash content, aluminum paste content and inc reasing water reducer content can improve the strength of grouting material with Id. By optimizing these factors, grouting material with50%CFBC fly ash, fluid ity of351mm,1d strength of22.5MPa is prepared.Humidity of curing has significant effect on expansion of CFBC fly ash. A dding CFBC fly ash can reduce the shrinkage of cement paste curing with not sat urated humidity and increase the linear expansion rate of cement paste curing at saturated humidity. Reducing the fineness of CFBC fly ash can release expansio n of system in advance and improve the volume stability. The expansion of CFB C fly ash in early time results from ettringite and dihydrate gypsum in the later. Grouting material with30%～50%CFBC fly ash could meet the requirements of t hat grouting material with micro expansion in early time and no shrinkage in the later stage.Exciting agent is helpful to improve the early strength of paste but not goo d to the fluidity. Multiple addition of0.02%triethanolamine and0.6%mirabilite can significantly improve the early strength of grouting material and have little effect on fluidity.0.03%slumping retaining or multiple addition of0.01%tartari c acid and0.05%sodium gluconate could reduce grouting material slump loses t hrough time and have a little effect on strength of Id. Grouting material with CF BC fly ash has a density structure and its long-term performance is good. |
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