| 초록 |
In general, fly ashes contain relatively higher levels of some heavy metals than bottom ashes. In spite of many efforts for the use of fly ash so far, most of fly ashes generated in this country are still buried in lands, leading to problems associated with the secondary contamination of soils and the increasing landfill burden. Polyurethane waterproof coatings (PW) are increasingly demanded in this country for repairing cracks on old building roofs and construction of many sports facilities. Calcium carbonate, CaCO3, is a common filler incorporated in PW compositions. Thus in this study, new PWs were prepared by substituting a part of calcium carbonate with fly ash as a filler. The maximum amounts of calcium carbonate to be substituted by fly ashes collected in the cyclone and bag filter dust collectors were 20 and 10%, respectively. The curing rates of the PWs could be easily controlled by varying the amounts of lead octoate as a catalyst. The elongations at break as well as tensile strength and tear strength of the PWs containing fly ashes could also be adjusted and comparable to or better than those of the commercial PW by varying relative amounts of some components. Thus, the PWs containing the fly ashes may be applicable to commercial uses.
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