FREEZE-THAW RESISTANCE OF CONCRETE USING GROUND GRANULATED BLAST FURNACE SLAG AND BLAST FURNACE SLAG SAND IN SALT WATER

Abstract

 The freeze-thaw resistance of concrete is significantly lower in salt water than in fresh water. Concrete deteriorates through repeated freezing and thawing, but in salt water, freezing alone leads to destruction. This paper investigated the effect of calcium hydroxide in concrete on the failure of concrete under such low temperatures. Calcium hydroxide precipitates at the interface between aggregate and cement paste due to the hydration reaction of cement. The lower the temperature and the higher the concentration of salt water, the more calcium hydroxide dissolves. From mortar, more calcium hydroxide is eluted in salt water than in fresh water. This accelerates the deterioration of mortar and concrete due to freeze-thaw action. Mortar and concrete using ground granulated blast furnace slag produce less calcium hydroxide. In mortar and concrete using blast-furnace slag sand, calcium hydroxide precipitated around the aggregate reacts with cement paste and blast-furnace slag fine aggregate to modify the interface. From these results, it was clarified that concrete using blast furnace slag exhibits high freeze-thaw resistance even in salt water.