## 1 Introduction  
The new global standards in relation to engineering have resulted in the development of recycled building materials, as an increased amount of energy-saving and eco-friendly infrastructure is required [1; 2]. Traditional concrete, the most frequently used building material worldwide, is known to result in severe environmental pollution because it uses both energy and raw materials in large quantities [3; 4]. Therefore, research on methods to minimize its negative impact on the environment is essential. For this reason, ground-granulated blast-furnace slag (GGBFS) and fly ash (FA), which are industrial byproducts, have been extensively used as substitutes of ordinary Portland cement (OPC), and many related studies have been conducted on this subject [5; 6; 7]. GGBFS and FA act not only as alkali-activated materials (AAMs), but also as supplementary cementitious materials (SCMs) [8]. If admixtures are used as SCMs, they can improve the durability, long-term strength, and constructability of the fabricated concrete [9; 10]. Geopolymers are a representative example of an admixture that may be used as an AAM. [PERSON] et al. [11] experimentally verified that GGBFS- and FA-based geopolymers can provide the excellent sulfuric acid resistance of recycled concrete. AAMs, however, are not yet used in the field due to their fast setting time, large shrinkage, and high unit price. Therefore, an in-depth study on the usability of SCMs is required to improve their construction site applicability. GGBFS is an industrial by-product, generated when producing pig iron. It turns into a granular and amorphous fine powder through quenching and grinding. GGBFS is mainly composed of SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), CaO, and MgO. Therefore, it can be called aluminosilicate, which uses CaO and MgO as its base components [12; 13; 14]. When in contact with water, GGBFS slowly undergoes a hydration reaction, and the reaction rate increases as the pH value is increased [10; 15]. [PERSON] et al. [16] conducted an experiment by replacing up to 80% of cement with GGBFS and reported that compressive strengths equivalent to that of OPC concrete were obtained when the mixing rate was 60% or less. In particular, they verified that GGBFS is effective in improving the long-term strength of concrete by confirming that the compressive strength was increased after 28 days of aging. In addition, [PERSON] et al. [17] found that the specimens for which cement was replaced with GGBFS exhibited 10% higher compressive strength than the plain specimen after 90 days of aging. They also reported that the specimens with GGBFS showed similar or higher compressive strengths than the conventional concrete after seven days of aging. Moreover, the durability of 100% OPC concrete could be improved by using GGBFS as an SCM [18]. The improvement of durable concrete is an important issue in relation to the extension of the service lives of concrete structures. It was verified that the use of GGBFS can improve the microstructures of concrete by adding a C-S-H phase, and it is effective in reducing the conductivity of chloride due to its provision of an increased alumina content [19]. [PERSON] et al. [20] conducted a 180-day immersion test with a 30% CaCl\({}_{2}\) solution and reported that the system with GGBFS and MgO endured damage far more effectively. [PERSON] et al. [21] claimed that the partial substitution of cement with GGBFS had a significant effect on the total flexural stiffness, corrosion rate, and permeability of a fabricated concrete beam. FA is a byproduct of coal-fired power generation and can be used as an SCM in concrete [22]. [PERSON] et al. [23] experimentally verified that the long-term compressive strength of concrete mixed with FA increases due to the continuous hydration process, even though its compressive strength decreases initially. They also reported that FA increases the sulfuric acid resistance of concrete but has a limited effect on reducing the corrosion potential of the steel reinforcement structures in concrete.