 Ground granulated blast-furnace slag

Ground granulated blast-furnace slag (GGBS or GGBF slag) is a byproduct from the iron-making industry. It is produced by rapidly cooling molten iron slag—a waste material generated during the extraction of iron from iron ore in a blast furnace—using water or steam, which results in the formation of a glassy granulated material. This granulated slag is then dried and finely ground to create a powdery substance.