expanded slag[ik′spand·əd ′slag]
(Russian, termozit), a man-made, porous aggregate for lightweight concretes. Expanded slag is produced by swelling melts of blast-furnace slag and subsequently rapidly cooling the melt in water. The cooled material is crushed and sorted out. The particles in expanded slag are irregular in shape, have rough surfaces, and have a size up to 40 mm and a porosity that ranges from 30 to 80 percent. The bulk weight of expanded slag ranges from 250 to 1,200 kg/cu m. Expanded slag is the cheapest porous aggregate in regions with developed metallurgical industries.