Improvement in mechanical properties and microstructure of electric arc furnace slag bricks by microbial accelerated carbonation

In this paper, the promising way to utilize EAF (electric arc furnace) slag as a cementitious material has been studied by employing microbially accelerated carbonation technology. Under the conditions of cation supplementation and accelerated carbonation of bacteria, the highest compressive strength of the samples could achieve 18 MPa in this research. The changes in minerals and microstructures during the carbonation and microbial carbonation have been observed by X-ray diffraction (XRD), thermogravimetric analysis (TG), and mercury intrusion porosimetry (MIP). Carbonic anhydrase-producing microorganisms have obvious acceleration effects in the carbonation process, making the matrix compact and improving the mechanical properties. Besides, the treatment method of accelerating carbonation by microorganisms could effectively inhibit the leaching of heavy metals in the EAF slag. This paper provides a reference for the potential applications of EAF slag in engineering and reveals the mechanism of microbial acceleration. Highlights Industrial waste electric arc furnace (EAF) slag was used as a cementitious material and could fix carbon dioxide. Microbial technology promotes the deposition of calcium carbonate (1–5 μm) to fill pores over 1 μm. Microbial accelerated carbonated EAF bricks could reduce the leaching of heavy metals.