Slag

Blast-Furnace Slag

Ground granulated blast-furnace slag, also calledslag cement, is made from iron blast-furnace slag; it is anonmetallic hydraulic cement consisting essentially of silicates

BLAST-FURNACE SLAG

Ground granulated blast-furnace slag, also called slag cement, is made from iron blast-furnace slag; it is anonmetallic hydraulic cement consisting essentially of silicates and aluminosilicates of calcium developed in amolten condition simultaneously with iron in a blastfurnace. The molten slag at a temperature of about 1500°C

(2730°F) is rapidly chilled by quenching in water to form a glassy sand like granulated material. The granulated material,which is ground to less than 45 microns, has a surface area fineness of about 400 to 600 m2/kg Blaine. The relative density (specific gravity) for ground granulated blast-furnace slag is in the range of 2.85 to 2.95. The bulk density varies from 1050 to 1375 kg/m3 .The rough and angular-shaped ground slag in the presence of water and an activator, NaOH or CaOH, both supplied by portland cement, hydrates and sets in a manner similar to portland cement. However, air-cooled slag does not have the hydraulic properties of water cooled slag. Ground granulated blast-furnace slag, when used in general purpose concrete, commonly constitutes between 30% and 45% of the cementing material in the mix. Some slag concretes have a slag component of 70% or more of the cementitious material. ASTM C 989(AASHTO M 302) classifies slag by its increasing level of reactivity as Grade 80, 100, or 120. ASTM C 1073 covers a rapid determination of hydraulic activity of ground granulated blast furnace slag and ACI 233 (1995)provides an extensive review of slag.