Recent research progress on the direct carbon capture of steel slag to prepare building materials

Driven by the “dual carbon” and “green metallurgy” targets, the steel industry feels the pressure of carbon emission reduction and steel slag resource utilization. Since the year 2000, accelerated carbonation technology using basic oxides in steel slag to store CO2 has been widely investigated worldwide. In this study, the chemical and mineral compositions and the main physical properties of different steel slags are summarized to achieve the dual purpose of CO2 mineralization and steel slag increment. This paper also summarizes the latest advancements in the direct carbonation of steel slag. Following the carbonation process, residual free calcium oxide and magnesium oxide can be further carbonated to aid in the preparation of building materials. The direct carbonation method improves the use of steel slag as an aggregate and in cementitious applications, exhibiting effective performance in steel-slag-based composites. Given the limited extent of steel slag carbonation and the modest utilization of available products, this paper explores the current research on carbonated steel slag for building material fabrication and discusses the variety of green building materials.