## 1 Introduction  
Concrete continues to be challenged relating to sustainability in relation to energy consumption, and greenhouse gas emissions [1]. In modern concrete structures, sustainability and high durability are essential in terms of minimal maintenance, economics, and extended service life [2]. A large quantity of industrial by-products is generated worldwide, and their safe disposal and recycling has become a serious problem [3; 4; 5]. One way to solve this problem is by using industrial by-products as supplementary cementing materials in concrete production, which can help reduce the carbon footprint of the cement production process. Therefore, ecofriendly or green concrete that uses industrial by-products, such as ground granulated blast-furnace slag, fly ash and silica fume, have been widely used since the 2000s to reduce CO\({}_{2}\) emissions [6; 7; 8; 9; 10; 11; 12; 13]. Stainless steel slag is an industrial by-product produced during the production of stainless steel. It generally has a different chemical composition according to the stainless steel production process and is classified as electric arc furnace slag or argon-oxygen decarburization (AOD) slag [14; 15; 16; 17]. The main component of AOD slag is 2 CaO-SiO\({}_{2}\) (C\({}_{2}\)S) [18]. AOD slag is produced by naturally cooling high-temperature melting slag to room temperature [15; 19]. In this cooling process, the C\({}_{2}\)S phase is transferred from \(\beta\)-C\({}_{2}\)S to \(\gamma\)-C\({}_{2}\)S, and AOD slag is naturally powdered during this transition [18; 20; 21]. Since \(\gamma\)-C\({}_{2}\)S does not have hydraulic properties, unlike \(\beta\)-C\({}_{2}\)S, AOD slag does not react with water [19; 22]. However, when CO\({}_{2}\) is present, \(\gamma\)-C\({}_{2}\)S reacts with water, as expressed in Equation (1). The products of this reaction are silica gel and CaCO\({}_{3}\)[23]. \[2(2\text{CaO})\text{SiO}_{2}+\text{CO}_{2}+3\text{H}_{2}\text{O}\to 3\text{CaO} \text{\textasciitilde{2 SiO}}_{2}\cdot 3\text{H}_{2}\text{O}+\text{CaCO}_{3} \tag{1}\]  
Using the reaction of \(\gamma\)-C\({}_{2}\)S with CO\({}_{2}\), as shown in Equation (1), studies have been conducted using AOD slag as a supplementary cementitious material [18; 21; 23; 24; 25]. [PERSON] et al. [23] studied the hardening behavior via accelerated carbonation of \(\gamma\)-C\({}_{2}\)S synthesized at 1300 \({}^{\circ}\)C. The compressive strength of the mortar specimen cured at 99.9% CO\({}_{2}\) for 24 h exceeded 60 MPa. However, the compressive strength of the specimen without CO\({}_{2}\) curing was only 0.19 MPa. They reported that this strength increase was owing to the increase in the amount of calcite produced by carbonation reaction. This was confirmed by thermogravimetry differential thermal analysis (TG/DTA). [PERSON] et al. [18] studied the hydration of AOD slag activated using a mechanical method. From the results of their experiments, it was confirmed that C-S-H and CH were generated as hydrated products of the activated AOD slag. [PERSON] et al. [24] investigated the mechanical properties of AOD slag under CO\({}_{2}\) curing and analyzed the chemical compositions of the products. They found that a compressive strength of 30 MPa or higher could be obtained in three weeks using CO\({}_{2}\) curing and examined the compressive strength according to the curing temperature. They also confirmed that the strength increase due to CO\({}_{2}\) curing was caused by the calcite and amorphous reactants produced by the carbonation of AOD slag. [PERSON] and [PERSON] [21; 25] studied the effect of CO\({}_{2}\) curing on strength for AOD slag cement pastes. They reported that the strength was increased due to densification of the micropores by the calcite and silica gel produced by CO\({}_{2}\) curing. A number of studies that utilize AOD slag as a cement substitute material have been conducted.