REFRACTORY PROPERTIES OF CONCRETE USING SINGLE MICRON FLY ASH AND GROUND GRANULATED BLAST FURNACE SLAG FINE POWDER

Abstract

In Japan, high strength concrete over 100 N/mm2 is generally used for high-rise buildings. In order to achieve a high strength of 100 N/mm2 or more, silica fume is used as an admixture. However, concrete using silica fume, when a fire occurs, concrete explodes, and the fire resistance performance deteriorates. Therefore, fibers such as polypropylene is used to improve fire resistance. But, since silica fume and fiber are expensive in Japan, there is a problem that the cost of concrete becomes high. Therefore, the authors examined the possibility of giving high strength and fire resistance to concrete by adding fly ash or blast furnace slag those are ground to the single micron region. In this study, fly ash and blast furnace slag with different particle sizes of 50% cumulative volume passage diameter of about 1 ~ 3 μm were used. In the experiment, fresh properties, compressive strength, and fire resistance of concrete were evaluated comparing to those of concrete using silica fume. As a result, for single micron fly ash, the larger the particle size is used, the better the fire resistance. Concrete using blast furnace slag showed no explosion at all levels. From the above, it was found that high strength concrete with refractory properties can be realized by using single micron fly ash and blast furnace slag fine powder.