Blast Furnace Slag
Blast Furnace Slag is formed when iron ore or iron pellets, coke and a flux (either limestone or dolomite) are melted together in a blast furnace. When the metallurgical smelting process is complete, the lime in the flux has been chemically combined with the aluminates and silicates of the ore and coke ash to form a non-metallic product called blast furnace slag. During the period of cooling and hardening from its molten state, BF slag can be cooled in several ways to form any of several types of BF slag products.
Blast Furnace: Combustion material and ore are supplied from the top while an air flow is supplied from the bottom of the chamber. This forces the chemical reaction to take place throughout the ore, not only at the surface.
Granulated slag is rapidly cooled by large quantities of water to produce a sand-like granule that is primarily ground into a cement commonly known as GGBS (Ground Granulated Blast Furnace Slag), or Type S slag cement. It is also mixed with Portland cement clinker to make a blended Type 1S cement.
Blast furnace slag is allowed to slowly cool by ambient air, is processed through a screening and crushing plant and is processed into many sizes for use primarily as a construction aggregate. Common uses are as aggregates in ready-mix concrete, precast concrete, hot mix asphalt aggregate, septic drain fields and pipe backfill.
Pelletized or Expanded Slag
Pelletized or Expanded Slag is quickly cooled using water or steam to produce a lightweight aggregate that can be used for high fire-rated concrete masonry and lightweight fill applications over marginal soils. Due to its reduced weight, it is perfectly suited for aggregate in lightweight concrete masonry, lightweight ready-mix concrete and lightweight precast concrete.
Air-cooled Blast Furnace Slag
This smaller sized aggregate is primarily used in chip and seal applications, also known as "Chip Seal" or "Aggregate Seal Coating", applied to existing pavement surfaces. The primary purpose for Chip and Seal is to achieve a skid resistance on rural pavements and to maximize driving safety. It is also used in concrete masonry and hot mix asphalt.
Air cooled blast furnace slag rip rap
The largest slag aggregate, riprap is a permanent cover of rock used to stabilize shorelines and streambanks, and prevent erosion along slopes and embankments. It is also used in gabion baskets, Mineral Wool manufacture (insulation), and lightweight fill.
Slag cement is commonly found in ready-mix concrete, precast concrete, masonry, soil cement, concrete wallboard, floor leveling compounds and high temperature resistant building products. Its measurable benefits in concrete include improved workability and finishability, high compressive and flexural strengths, and resistance to aggressive chemicals.
Steel Furnace Slag
Steel Furnace Slag is produced in a (BOF) Basic Oxygen Furnace or an (EAF) Electric Arc Furnace. Hot iron (BOF) and/or scrap metal (EAF) are the primary metals to make steel in each process. Lime is injected to act as a fluxing agent. The lime combines with the silicates, aluminum oxides, magnesium oxides, manganese oxides and ferrites to form steel furnace slag, commonly called steel slag. Slag is poured from the furnace in a molten state. After cooling from its molten state, steel slag is processed to remove all free metallics and sized into products.
Basic Oxygen Furnace (BOF)
Oxygen is blown into the furnace vessel through a water-cooled oxygen lance oxidizing carbon and the other unwanted elements in the molten iron. Fluxes are added to remove other unwanted elements yielding high quality steel.
Electric Arc Furnace (EAF)
Charged material is heated to a liquid state by means of an electric current. The electricity has no electrochemical effect on the metal making it perfectly suited for melting scrap.
Steel slag is processed as an air-cooled material. The free metallics are magnetically separated and sized into construction aggregates, used as an agricultural soil amendment, as a raw ingredient in Portland cement production, as an environmental remediation material and other uses.
Steel Slag has evolved as an ideal aggregate in Hot Mix Asphalt (HMA) surface mixture applications. Where friction is an important safety consideration in pavement design for the motoring public, properties of Steel Slag qualify it as a premier surface aggregate for skid resistant applications. With the development and implementation of Superpave technology throughout the United States as well as the further expansion of Stone Matrix Asphalt (SMA) mixes for severe traffic and axle-loading applications, Steel Slag has earned the distinction as a premium surface aggregate. In addition, Steel Slag continues to be recognized as a standard for use in both Seal Coating and Cold Patching applications.
Chip and Seal
Also known as "Chip Seal" or "Aggregate Seal Coating", this is a single or double application of Bituminous Surface Treatment applied to existing pavement surfaces. The primary purpose for Chip and Seal is to achieve a skid resistance on rural pavements and to maximize driving safety for the general public. The use of Chip and Seal is a cost effective way to improve the safety and integrity of a road surface in low traffic environments.