## 1 Introduction  
The current world housing deficit is estimated to be 1.3 billion [1] and the infrastructure investment gap by 2040 is expected to be around 15 trillion (\(10^{12}\)) dollars [2]. Both industries (construction and infrastructure) consume a large amount of Portland cement (PC), contributing to its elevated demand, with an average annual global production of 4.0-4.2 Gt [3]. As a downside of this large production, the PC industry is responsible for 8% of the global greenhouse gas emissions [4], which demands the development of alternative and cleaner binders that may replace PC in its applications. Alkali-activated materials (AAMs) have been promoted as alternative greener building materials in recent decades. One of the main reasons for this is that AAMs can be designed to lower greenhouse gas emissions by employing industrial residues as raw materials during the production process [5]. The global warming potential impact of AAMs was estimated to be between 45% and 80% lower than PC depending on the raw materials used [6, 7, 8]. The main benefits of AAMs are a low CO\({}_{2}\) footprint by valorizing industrial wastes, high mechanical performance, potentially high chemical resistance and the capacity to encapsulate hazardous wastes [9, 10, 11, 12, 13, 14, 15]. AAMs are derived from the reaction of aluminosilicate sources with an alkaline solution [16]. The conventional approach is to combine an alkali-activator solution (i.e., hydroxides or silicates of sodium or potassium) with an amorphous aluminosilicate powder, usually ground-granulated blast furnace slag (GGBFS); pulverized fly ash (PFA); calcined clays, such as metakaolin (MK); or glass waste. The alkaline activation results in either an alkali aluminosilicate gel or a calcium aluminosilicate hydrate gel or the coexistence of both [17; 18]. However, the supply of those three main precursors is now challenging: GGBFS already has a well-defined route of utilization apart from AAMs (i.e., as supplementary cementitious material replacing PC); PFA availability was significantly reduced due to the continuous decommissioning of coal power plants worldwide [19] and MK is a natural resource. Consequently, there is a need for finding alternative binders to replace these and meet the future demands of AAMs. Steel slag (SS) is the main solid waste (over 90% by weight) generated by the steelmaking industry. According to the World Steel Association, more than 270 million tons of SS were generated in 2019 [20]. Typically, this amount is stockpiled in open fields, causing environmental harm and financial liability [21]. Furthermore, China and Brazil, which are two important crude steel producers, reuse less than 30% of the SS generated [21; 22]. The conversion of iron into steel in a basic oxygen furnace (BOF), also known as the Linz-Donawitz (LD) process, is a widespread process used by the steel industry, where molten iron is combined with steel scraps and fluxes to produce steel and generate BOF slag [23]. The former usually consists of CaO (30-60%), Fe\({}_{2}\)O\({}_{3}\) (3-38%), SiO\({}_{2}\) (7-20%), FeO (7-35%), Al\({}_{2}\)O\({}_{3}\) (1-6%), MgO (1-15%), MnO (2-8%) and P\({}_{2}\)O\({}_{5}\) (1-5%). The common mineral phases are dicalcium silicate (C\({}_{2}\)S), tricalcium silicate (C\({}_{3}\)S), tetra-calcium aluminoferrite (C\({}_{4}\)AF), olivine, merwinite, CaO-FeO-MnO-MgO solid solution and free CaO [24]. The volumetric expansion of the SS [25] and its low reactivity [26] are the most critical challenges to ensuring application in PC-based materials. Despite this, several studies continue to be published that evaluate SS's potential as supplementary cementitious material even though low percentages of SS are employed [27; 28; 29; 30]. Regarding the development of AAMs, most recent studies were carried out using SS as a partial replacement in blends with other precursors [31; 32; 33; 34; 35; 36; 37; 38; 39; 40] or using SS as the sole precursor in the matrix [41; 42; 43; 44; 45; 46; 47; 48].