The Incorporation of Ladle Furnace Slag in Fire Insulating Gypsum-Based Materials

Abstract

Ladle slag, a byproduct of steel manufacturing, exhibits inherent reactivity and undergoes hydration when exposed to water. Nevertheless, these reaction byproducts often remain metastable, leading to microstructural alterations when incorporated into cementitious materials, thereby limiting the recycling potential of ladle slag. This study explores the fire insulating capacity and the physical, mechanical, and leaching characteristics of gypsum-based materials with substantial quantities of ladle slag in instead of gypsum. The mechanical strength of the specimens declines as the ladle slag content increases. Nevertheless, the percentage decrease in compressive strength at various temperatures (300 °C, 500 °C, and 700 °C) is less pronounced when higher amounts of ladle slag are used. Fire-resistant properties, assessed using the EN 1363-1 standards, diminish with increasing slag proportions; although the inclusion of ladle slag introduces certain endothermic processes that positively affect the fire insulating capacity, resulting in a 20% reduction when 60%wt of slag is employed. Notably, no gas emissions were observed during the fire test, indicating the absence of environmental hazards. In conclusion, ladle slag does not pose a leaching threat to the environment, making it a viable and sustainable alternative to gypsum in gypsum-based materials.