Blast Furnace Slag as Sustainable Material in Concrete Pavements

Slag materials are byproducts of metallurgical processes that include metal production from ore and refinement of impure metals. Air-cooled blast furnace slag (ACBFS) has been used for different pavement-related applications. Appropriate use of ACBFS can significantly enhance sustainability, rather than disposing of it, by effectively contributing to all aspects of the “triple bottom line.” Proper use of ACBFS can also result in economic, environmental, and social benefits as long as the performance of the concrete structure is not compromised through such use because any short-term economic and environmental gain would be rapidly eclipsed by the economic, environmental, and social costs of poor pavement performance. Thus, it is essential that engineers and contractors who use ACBFS aggregates in concrete understand its unique properties to make sure that the expected performance of the pavement over its design life is achieved. The chemical composition of ACBFS may affect its performance and has to be considered when ACBFS is used as a coarse aggregate. Physical properties of ACBFS, such as texture, absorption, and specific gravity, also have to be considered when ACBFS is used in concrete. ACBFS also affects fresh and hardened properties of concrete. Specific design, construction, and quality control considerations have to be taken into account when ACBFS is used. In this paper, sustainability aspects of using ACBFS as a coarse aggregate in concrete pavements and considerations for its use in this application are presented. A best practices guideline recently published by FHWA presents the same discussions in more detail.