The slag would normally be considered a waste product and sent to a landfill. However, while in its molten state, slag is quenched with water and forms granules of glass consisting of silicates and aluminosilicates of calcium. These granules are then ground to a fine powder and are able to react with water, similar to Portland Cement. This Ground Granulated Blast Furnace Slag may be blended with Portland Cement to achieve the following benefits:

• Increased concrete strength and durability
• Increased concrete reflectivity
• Better concrete workability
• Improved finishability
• Lower concrete permeability
• Improved resistance to chemical attack
• Reduced virgin material in the manufacture of concrete
• Reduced embodied greenhouse gas emissions
• More consistent plastic and hardened concrete properties

Slag has been effective in replacing up to 50 percent of Portland cement in structural and paving applications, as well as up to 80 percent in high-performance and mass concrete applications. To learn more about how slag compares to standard Portland cement, click here.

In 1996 the Environmental Protection Agency recognized slag cement as a “recovered” product under the Federal Resource Conservation Recovery Act. This classification requires that slag cement be specified in concrete on federally funded projects.

For more information on slag cement please visit the Slag Cement Association at www.slagcement.org