Specific weight of blast-furnace slag in 1 m³, volumetric weight and density

Slags are artificial silicate materials formed during metallurgical processes. A slag melt may contain compounds of silicon, iron, calcium, manganese, sulfur and other elements. After cooling, the melt can turn into a dense stone-like mass or a porous material similar to pumice. The final structure depends on the oxide composition and cooling rate.

In appearance, slags resemble natural rocks: they may be green, yellow, gray, pink, white, black or mixed in color. By structure, this industrial raw material can be dense or porous, heavy or lightweight.

Slag density can vary from about 800 to 3200 kg/m³. The true density of slag substance is close to that of natural stone materials and is often in the range of 2.5 - 3.6 g/cm³. During metallurgical processing, slag must be lighter than molten metal so that it rises to the surface of the melting bath and separates from the metal.

Types of slag melts and their formation process

The construction industry actively uses industrial raw materials of metallurgical origin. Such material has already been exposed to high temperatures, has a formed mineral structure and can be used as an aggregate or component of building materials. Metallurgical production by-products are commonly divided into:

• ferrous metallurgy waste;
• non-ferrous metallurgy waste;
• steelmaking slags.

The most common raw material for construction materials

One of the most common technogenic materials is blast-furnace slag from ferrous metallurgy. It forms during pig iron smelting in a blast furnace and contains components of gangue, fluxes and fuel ash. The amount and properties of slag depend on the raw material composition, sulphur content, lime input and the level of the technological process.

Common types of metallurgical slag considered as technogenic raw material include:

• blast-furnace slag;
• steelmaking slag;
• open-hearth slag;
• cupola slag.

Each type differs in composition, density, porosity and suitability for specific construction materials. Laboratory testing, a quality certificate and a safety assessment are therefore important before use.

Blast-furnace slag is used to produce slag crushed stone, granulated slag, cement additives, slag concrete and other construction materials. The average mass of lump material is often around 2500 kg/m³, but depending on condition and structure it may vary from 2100 to 2800 kg/m³.

For practical calculations it is convenient to use ready values for the weight of 1 m³ of blast-furnace slag depending on its state: slag crushed stone, lump slag or slag concrete. These approximate data are shown in the table above.