## 1 Introduction  
The world's annual population is continuously increasing by 1.05% on average, with an increase of 81 million people in 2020 [1]. This growth seems to be proportionally linked to the rising demand for housing and other infrastructure that will simultaneously increase the need for construction materials, such as Portland cement. In 2016, the amount of cement produced worldwide reached 4.2 billion tonnes, 57% of which was produced by China alone [2, 3]. It is a well-known fact that for each one tonne of cement produced, around 0.5-0.6 tonnes of CO\({}_{2}\) (0.59 according to IEA, 2020 [4]) are being released into the atmosphere, meaning that in 2016, the cement industry itself released nearly 2.5 billion tonnes of CO\({}_{2}\), which accounted for 8% of the global CO\({}_{2}\) emissions of the same year [5, 6]. Solving this issue cannot be done by cutting the production of cement alone; other cement-replacing materials need to be found to meet the growing demand for this vital building material. Alkali-activated materials (AAM) are a relatively recent technology as integral cement replacement in the production of concrete and with reduced environmental impact and cost [7]. However, some of the precursors generally used for their production, such as ground granulated blast furnace slag (GGBFS) and fly ash (FA), are facing shortage in availability [8]. To maintain a constant flow in the supply chain, other aluminosilicate waste precursors, prone to little variation in yearly production over time, are needed. One contender is the electric arc furnace slag (EAFS), as the steel industry is shifting from new steelmaking to a recycling system, consequently reducing the amount of GGBFS. It has an aluminosilicate-rich chemistry giving it the possibility to be the next cement-replacing AAM used in concrete. In terms of availability, about 190-290 million tonnes of steel slag are generated each year, 15-20% of which are EAFS [9]. EAFS generation is based on the recycling of scrap metal and pig iron that can be limited at some locations [10]. It is being used mostly as an aggregate substitute for road base course layers and asphalt pavements [11; 12], which is a downcycling process from what they can actually offer. According to several studies [12; 13; 14; 15; 16; 17; 18; 19; 20; 21], EAFS has led to notable improvements in mechanical strength when used as coarse and/or fine aggregates replacement. However, its richness in calcium oxide (free-CaO) and Ferric oxide (FeO) has pushed researchers to further explore the possibility of using EAFS as a cement substitute [22; 23]. [PERSON] and [PERSON] [24] found that any silica-alumina source material that has a pozzolanic component is suitable for dissolution in alkaline solutions. Since EAFS is rich in aluminium and silica, it is desirable to examine whether its activation in alkaline solutions can occur, considering this knowledge [25; 26]. The use of EAFS as partial or full cement replacement has led to improvements in mechanical and microstructural performances [25; 27]. [PERSON] et al. [28] conducted an experimental study to understand the mechanical performance of partially replaced clinker with EAFS. The study concluded that a compressive strength of 50 MPa can be achieved with 30% clinker-EAFS replacement, compared to 58 MPa with 20% replacement and 58.6 MPa for the reference specimen with 100% cement. It has also been found that the substitution of untreated EAFS with treated EAFS can lead to an increase in strength [28]. Another study has recorded a 28-day compressive strength of 44.38 MPa using 25% EAFS as cement replacement compared to 59.34 MPa for the reference specimen with 100% cement [29]. Moreover, [PERSON] et al. [30] investigated the influence of cement's partial substitution with EAFS, focusing on the EAFS' particle distribution.