The expansion of circulating fluidized bed fly ash (CFA) and the effect of CFA content,fineness of CFA and curing regimes on the expansion properties of cement paste were investigated.Moreover,the mechanism of expansion of CFA was discussed by XRD and SEM,as well as the control measure.The results indicated that the formation of ettringite in 7 days after the hydration of CFA results in expansion and relative humidity has significant effect on the expansion of CFA.Mechanical grinding can improve activities of CFA and release the expansion in early stage,adding aggregate and improving early strength are effective ways to control expansion.
