Influence of aggregate type on mortar thermal stability

Abstract

217-224<span style="font-size: 13.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">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 line aggregate for replacement of sand on the mechanical and chemical properties of mortars exposed to lire at different temperatures. Mortar mixes were prepared with three different water cement ratios (0.4, 0.5, and <span style="font-size: 13.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">0.6) and cured in potable water for 90 days, then kept in laboratory atmosphere conditions for about four months. They were exposed to lire at temperatures of 300,400, 500, and 600°C for 2 h soaking time followed by rapid cooling in water. Results <span style="font-size: 13.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">of this investigation indicated that the compressive strength of mortars exposed to lire was gradually decreasing with increasing temperature of fire up to 500°C, while it significantly decreased when temperature reached 600°C. The use of air cooled <span style="font-size:13.0pt;mso-bidi-font-size:8.0pt;line-height:115%; font-family:" times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";="" mso-fareast-theme-font:minor-fareast;mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">slag improved the thermal stability of mortar.</span