Structural Fill of Steel Slag Caused Heave of a Building

The results of an investigation on the cause of damage to a two-story industrial building supported on 5.5m of steel slag fill in the town of Monclova in the north of Mexico are presented. Since six years it was built, the floor slab heaved between 2om and 25om. The columns were raised up between 2 cm and 20 cm. These movements cracked the building. Chemical analysis of slag showed 22% of calcium oxide and 5% of magnesium oxide, which on hydration cause swelling. At a distance of 4m on one side of the building was a hearth-bath, a molten iron pit, 5mx5m & 4m deep c0nstructedin the same slag fill. The heat transmitted from the hearth-bath to the fill beneath the building caused it to swell. The swell was proportional to the heat transmitted. The maximum heave was 25 cm at a distance of 4 m from the heat source. The heave decreased at increasing distances from the heat source