Benefits of Slag
Blast furnace slag and steel slag are the aggregates of choice in many industries. Both types of slag offer a wide range of benefits over alternative aggregates.

Benefits of Blast Furnace Slag
Benefits of Steel Slag

Benefits of Blast Furnace Slag
Blast furnace slag is a versatile, economical byproduct of production of iron. The four distinct methods of processing molten blast furnace slag - air cooled, expanded, pelletized and granulated - produce unique materials, although all varieties of blast furnace slag share basic advantages over other aggregates.

With a lower specific gravity and greater surface area than most natural aggregates, blast furnace slag is ideal for construction and architectural applications. A lower unit weight than most natural aggregates makes blast furnace slag economically efficient. Durable, strong, and lightweight, blast furnace slag offers high resistance to sulfate attack and alkali-silica reaction. Superior thermal properties, sound absorption and reduced weight loads make blast furnace slag a logical and versatile building material.

Many architectural applications require strength, durability with lighter materials. Densities can be controlled in the manufacturing process. Masonry units made with blast furnace material weigh less thus contributing to a reduction in shipping and handling costs. Air cooled blast furnace slag weighs in as a great value when compared to tons per cubic yard of alternative aggregates.

Air Cooled Blast Furnace Slag (ACBF) vs. Alternative Aggregates
Tons Per Cubic Yard Factors Published by AASHTO

AASHTO SizesACBF SlagLimestoneSandstoneGravel
Bases1.36 (2720)1.46 (2920)1.46 (2920)1.46 (2920)
3-1/2" - 1-1/2"1.04 (2080)1.30 (2600)1.30 (2600)1.30 (2600)
2-1/2" - 1-1/2"1.04 (2080)1.30 (2600)1.30 (2600)1.30 (2600)
2" - 1"1.04 (2080)1.30 (2600)1.30 (2600)1.30 (2600)
2" - 1"1.04 (2080)1.30 (2600)1.30 (2600)1.30 (2600)
2" - 1"1.04 (2080)1.30 (2600)1.30 (2600)1.30 (2600)
Chips1.20 (2400)1.32 (2640)1.32 (2640)1.32 (2640)
Blended 2 x 01.40 (2800)1.70 (3400)1.70 (3400)1.70 (3400)
Numbers in parenthesis are Pounds Per Cubic Yard


Masonry and walls made with various types of blast furnace material have higher levels of fire resistance than those made with clay, shale or gravel aggregates.

Fire Resistance Ratings

(American Insurance Association)
Walls and Partitions
Minimum Equivalent Thickness for Ratings of
Type of Coarse Aggregate4 hrs.3 hrs.2 hrs.1 hr.
Expanded Blast Furnace Slag or Pumice4.74.03.22.1
Expanded Clay or Shale5.74.83.82.6
Limestone, Cinders or Air Cooled Blast Furnace Slag5.95.04.02.7
Calcarious Gravel6.25.34.22.8
Siliceous Gravel6.75.74.53.0


The benefits of blast furnace slag are widespread and continue to grow. Call Stein to learn more about how our blast furnace slag can improve your processes - and your bottom line.

Benefits of Steel Slag
Steel slag has evolved into a premier construction aggregate for many specialized applications. Steel slag's unique physical and chemical composition qualifies it as the most viable product for meeting the technical and fiscal requirements of many market segments. Some of the most popular uses for steel slag include:

  • Hot Mix Asphalt (HMA) Aggregate
  • Portland Cement
  • Road Shoulders
  • Unconfined Road Base
  • Soil Remediation
  • pH Neutralization of Abandoned Mines & Contaminated Sites

Skid resistance has proven to be one of the greatest benefits of steel slag over other natural aggregates for roadway paving. With safety in mind, many road agencies require the use of steel slag when skid resistance is of prime concern. The physical properties and surface texture of steel slag provides a coefficient of friction in bituminous surface courses higher than most natural aggregates. Furthermore, steel slag's resistance to polishing means that it's frictional benefits are maintained over time.

Cement production is another area where steel slag has proven especially beneficial over other aggregates. Steel slag undergoes calcination during it's production which removes most volatile materials and CO2. Therefore, using Steel Slag in cement manufacturing improves clinker production and reduces CO2 emissions. Furthermore, the amount of fuel needed to produce one ton of clinker is reduced because the heat of decarbonation is eliminated. To illustrate the benefit, consider this statistic: one ton of limestone's yield contribution of cement clinker can be as low as 60%, while Steel Slag's yield is 100%.

The benefits of steel slag are widespread and continue to grow. Call Stein to learn more about how our blast furnace slag can improve your processes - and your bottom line.

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