Influence of aggregate type on mortar thermal stability

The contributions of components, especially aggregates, to the fire resistance of mortar and concrete have been studied. Blast-furnace slag, as a by-product from iron and steel industries, is allowed to cool slowly in air to form dense slag or to cool very rapidly in water to form granulated slag. The present work aims to study the effect of using crushed air-cooled and water-quenched slags as a fine aggregate for replacement of sand on the mechanical and chemical properties of mortars exposed to fire at different temperatures. Mortar mixes were prepared with three different water cement ratios (0.4, 0.5, and 0.5) and cured in potable water for 90 days, then kept in laboratory atmosphere conditions For about four months. They were exposed to fire at temperatures of 300, 400, 500, and 600 degreesC for 2 h soaking time followed by rapid cooling in water. Results of this investigation indicated that the compressive strength of mortars exposed to fire was gradually decreasing with increasing temperature of fire up to 500 degreesC, while it significantly decreased when temperature reached 600 degreesC. The use of air-cooled slag improved the thermal stability of mortar.