## 1 Introduction  
As the demand for steel has increased during the current era of rapid economic development, the production of industrial by-products, such as blast furnace slag, has also increased around the world. The accumulation of blast furnace slag is a form of pollution, which represents a significant environmental problem. About 2.4 million tons of slag is produced every year, and only a small amount of this is used efficiently, meaning most of the remainder is considered to be solid industrial waste [1, 2]. The slag has been used in the past as a substitute for Portland cement in concrete production due to its latent hydraulicity [3]. The workability and mechanical performance of concrete with slag cement (with the content of slag used as 25% replacement of the weight of the cement) were investigated by [PERSON] et al. [4]. [PERSON] [5] studied the chloride diffusion, sulfate resistance, and permeability of the concrete mixed with slag as the replacement for cement. Furthermore, the production of conventional Portland cement is responsible for considerable atmospheric pollution, including carbon dioxide emissions. Blast furnace slag can be applied completely, using an alkali-activator, in place of Portland cement. As a result, there have been many investigations on the potential utilization of blast furnace slag in the production of building materials for the construction industry to help preserve natural resources, reduce pollution, and thus better maintain ecological balance. Alkali-activated cementitious material is an inorganic binder consisting of a mixture of alkaline activator and silicate cementitious materials, such as fly ash, metakaolin, phosphorous slag, steel slag, or blast furnace slag [6]. Many researchers have indicated that alkali-activated slag concrete (AASC) provides excellent mechanical performance [7; 8], good durability [9; 10], and fast setting times [11; 12]. In general, the key parameters determining the properties of AASC are the composition of materials, type of alkaline activator, and the admixtures used [11; 13; 14]. The workability of alkali-activated slag (AAS) pastes has been found to be better and the slump higher as the liquid-to-solid ratios increase from 0.45 to 0.60, but the compressive strength is typically lower [15]. It has also been reported that a higher content of alkali agent decreases the setting time and increases the compressive strength and ultrasonic pulse velocity in AAS pastes [16]. The compressive strength of AASC has been found to increase notably in the first three days to about 3.5-5 times the level of ordinary Portland cement [17]. The compressive strength of AASC activated by sodium silicate solution can reach 64.5 MPa, which is much larger than that by sodium hydroxide (15.6 MPa) after 28 days [7]. The main reason for this is that the slag activated by sodium hydroxide forms a denser C-S-H with less chemically bound water in the initial reaction, which results in an increase in coarse porosity at a later age and lower mechanical performance [18]. However, there is an opposite trend in terms of the drying shrinkage of AAS activated by the above two alkaline activators [19]. A direct relationship has been observed between drying shrinkage and pore structures [20], with finer pore size distribution resulting in increased drying shrinkage while improving the compressive strength [21; 22]. The silicate modulus and alkali content have been found to be the main parameters for the properties of the slag activated by water glass [23; 24; 25]. The optimum silicate modulus and sodium concentration in terms of fresh and hardened properties of AAS are due to the excess alkali being unable to fully react with the slag [26]. A previous study determined that the compressive strength, permeability, water sorption, and carbonation resistance properties of AASC can be improved with higher binder contents [8], resulting in an AASC with a refined, complex, and closed porous structure [20].