Abstract Steel slag is an emerging supplementary cementitious material (SCM) that can reduce the carbon footprint of cement. This study reports the use of an electric arc furnace (EAF) slag from new steelmaking process i.e. direct hydrogen-assisted iron reduction (i.e., H 2 -DRI-EAF route) as an SCM. Further analysis was conducted to examine the effects of carbonation methods including semi-dry and aqueous carbonation on the hydration of slag in blended cements. The results indicate that the carbonation of the slag led to the formation of amorphous silica, crystalline and amorphous CaCO 3 which contributed to the hydration reactions in blended cement. The pozzolanic activity and hydration behavior of carbonated slag were further assessed using R 3 test and isothermal calorimetry while SEM–EDS, XRD, and TGA were used to analyze the phase transformations after carbonation. Between the two carbonation methods, the aqueous carbonation led to a higher CO 2 uptake (9.5 g/100 g slag) and better reactivity. This is due to the formation of more reactive phases such as amorphous silica and calcium carbonates which linked to diverse hydration product formation such as C-(A)-S–H, AFt and hydrotalcite. The compressive strength showed an increase of 53 and 7% at 7 and 28 days of hydration in slag-blended samples compared to limestone-based blend. The findings reveal that the EAF slag from this novel steelmaking process is suitable for carbonation and utilization as SCM. Graphical Abstract
Gouda et al. (Fri,) studied this question.