1. Scope

Keywords

Rationale

The proposed standard is needed to support the responsible and technically sound use of processed electric arc furnace (EAF) slag as a supplementary cementitious material (SCM) in concrete and mortar. Unlike ground granulated blast-furnace slag (C989) or pozzolans (C618), EAF slag is not currently covered by any ASTM product specification, despite its emerging relevance as a valorized industrial by-product with potential to reduce clinker factor and embodied carbon in concrete. EAF steelmaking is rapidly expanding in many markets due to its compatibility with scrap recycling and lower direct CO2 emissions compared to traditional blast-furnace routes. As EAFs become a more dominant steel production method globally, the volume of EAF slag available for beneficial use is increasing. Establishing a clear specification for this material will help enable EAF slag uptake as a cement replacement, supporting circular economy goals, industrial decarbonization, and improved resource efficiency. This standard will provide material requirements, performance benchmarks, and reference test methods. Primary users of the standard will include SCM producers and processors, cement and concrete manufacturers, ready-mix suppliers, materials specifiers, construction contractors, and public and private infrastructure owners. The specification will also assist regulatory agencies and certification bodies in recognizing EAF slag as a viable SCM. A parallel revision to ASTM C125 is proposed to formally introduce terminology for "electric arc furnace slag" and other relevant steel slags, ensuring consistency and traceability across standards.