In general, silica fume is used as admixture to product high-strength concrete. On the other hand, researches on utilization of ground granulated blast furnace slag as an alternative material for silica fume have been begun in recent years. However, no researches has been conducted on long-term strength characteristics and durability of high -strength concrete using ground granulated blast furnace slag.
In this study, the long-term strength characteristics and durability of high-strength concrete using ground granulated blast furnace slag fine powder with specific surface area of 12000 and 16000 cm2/g (hereinafter referred to BFS concrete) were researched and compared with that of concrete using silica fume (hereinafter referred to SF concrete).
Results obtained from this study are summarized as follows.
1) From results of temperature rise tests using adiabatic curing specimens, temperature rise of BFS concrete is larger than that of SF concrete by 20% for water binder ratio of 22%, and by 12 to 14% for water binder ratio of 25%.
2) Compressive strength of concrete under standard curing was continued to increase up to the age of 8 years in both BFS concrete and SF concrete. In standard curing, the strength ratio of BFS concrete to the SF concrete was 0.89 to 1.09 in the period of 3 days to 8 years of age. In addition, the strength ratio of BFS concrete to the SF concrete was 0.93 to 1.08 at 8 years. The difference in strength ratio of both concretes was within range of ± 8%.
3) Compressive strength of core specimen was continued to increase up to the age of 20 years in both the BFS concrete and SF concrete. About the core specimens, the strength ratio of BFS concrete to the SF concrete was 0.94 to 1.06 in the period of 28 days to 20 years of age. In addition, the strength ratio of BFS concrete to the SF concrete was 0.96 to 1.05 at 20 years. The difference in strength ratio of both concretes was within range of ± 5%.
4) Shrinking of BFS concrete at the drying period of 10 years is smaller than that of SF concrete by 5 to 12%.
5) Carbonation depth at 20 years for outdoor exposure was 0mm in BFS concrete and SF concrete.
6) From the result of freezing and thawing test at 400 cycles, durability of BFS concrete was equal to or greater than that of SF concrete.
In the scope of this study, it is proved that ground granulated blast furnace slag with large specific surface area can be used as an alternative material for silica fume to product high-strength concrete.
