A PRELIMINARY ASSESSMENT ON REUSAGE OF FLY-ASH EMITTED FROM FLUIDIZED-BED INCINERATION OF SLUDGE CAKE

Reusage or recycle of flyash can eliminate the cost of final disposal and prevent secondary pollution caused by inappropriate flyash disposa l. It is well known that the flyash emitted from fluidized bed inciner ation (FBI) is fine particle. Moreover its properties are more similar to concrete than that of ash from other incinerators. A promising and economical reusage of flyash is in concrete material. Prior to this a pplication, it is necessary to explore the characteristics of cement m ixed with flyash. Besides analyzing the general physical and chemical properties of FBI flyash, this article presents a preliminary assessme nt on reusage of FBI flyash in concrete by a series of experimental te sts on the characteristics of flyash-cement paste, including the macro characteristics of fresh cement paste e.g. workability, bleeding water , setting time, compressive and tensile strengths, and micro-character istics, e.g. paste hardening, pore distribution, and crystal structure . Effects of flyash amount in the paste and of flyash size on these pr operties are also studied. An approach to evaluate the reusage of flya sh by inspecting the characteristics of flyash-cement paste is propose d, and leads to a potential reusage scheme for the FBI flyash as a con crete material resource. (C) 1997 Elsevier Science B.V.