Slag materials are by-products of metallurgical processes that include metals production from ore and refinement of impure metals. Air-cooled blast furnace slags (ACBFS) have been used for different pavement-related applications.
Appropriate use of ACBFS rather than disposing of it can significantly enhance sustainability by effectively contributing to all aspects of the “triple-bottom line” resulting in economic, environmental, and social benefits as long as the performance of the concrete structure is not compromised through the use of ACBFS because any short-term economic and environmental gain will 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 will be achieved.
Chemical composition of ACBFS may affect its performance and has to be considered when using it as a coarse aggregate. Physical properties of ACBFS such as texture, absorption, and specific gravity also have to be considered when using ACBFS in concrete. ACBFS also affects fresh and hardened properties of concrete. There are specific design, construction, and quality control considerations that have to be taken into account when using ACBFS.
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 the Federal Highway Administration (FHWA) presents the same discussions in more detail.