## 1 Introduction  
Cement is an inorganic hydraulic powder material with good workability, mechanical properties, and durability, making it the most widely and commonly used building material worldwide [1]. However, cement production is often associated with mineral resource shortage, excessive energy consumption, and excessive CO\({}_{2}\) emissions. It is reported that for every 1 ton of cement produced, \(\sim\)800 kg of CO\({}_{2}\) gas is generated. Moreover, the total emissions from cement production account for \(\sim\)8% of the world's total CO\({}_{2}\) emissions, making cement production a significant contributor to the carbon emission industry [2, 3]. With the intensification of the global greenhouse effect, energy conservation and carbon reduction have become the future development directions of the cement industry. Therefore, many scholars have proposed the utilization of various industrial solid wastes (such as fly ash, granulated blast-furnace slag [GBFS], and silica fume) as supplementary cementitious materials [4; 5; 6]. These materials not only exhibit certain hydration abilities but also play a role in filling pores. Accordingly, a series of green and low-carbon cementitious materials have been developed [7; 8; 9]. GBFS is a byproduct of the iron-making process. It contains numerous silico-aluminate minerals and exhibits a volcanic ash effect [10; 11]. Generally, GBFS activity can be stimulated by alkali, sulfate, and other materials, as shown in Table 1 in Appendix A.  
Carbide slag (CS) is a byproduct of industrial acetylene production, and its main components are Ca(OH)\({}_{2}\) and a small amount of CaCO\({}_{3}\)[12; 13]. In recent years, CS production has steadily increased with the growing demand for acetylene, reaching an expected annual production of \(\sim\)5.6 \(\times\) 10\({}^{7}\) tons per year. Using CS is quite challenging, owing to its high alkalinity. Most enterprises opt for on-site storage [14; 15], and there is still untapped potential yet to be explored. This paper discusses utilizing CS as an alternative to an alkali activator to enhance GBFS activity, aiming to reduce costs and mitigate the environmental issues associated with alkali activators. Numerous studies have demonstrated that CS possesses a certain alkali excitation effect. The combination of CS and GBFS yields the best effect, but adding some auxiliary material is often required to obtain ideal strength [16; 17; 18]. Electolytic manganese residue (EMR) is an industrial solid waste produced through the electrolysis of metallic manganese, and its main components include CaSO\({}_{4}\cdot\)2H\({}_{2}\)O and SiO\({}_{2}\)[19]. It has been reported that every ton of electrolytic manganese production results in the generation of 10 to 12 tons of EMR. Over the years, the cumulative amount has exceeded 150 million tons, with an annual utilization rate of only \(\sim\)10%. This is attributed to the complex composition of EMR, which includes harmful ions such as Mn\({}^{2+}\), Cd\({}^{2+}\), and NH\({}_{4}\)\({}^{+}\)[20; 21]. At present, most enterprises resort to open-air stacking and in situ burial methods, which have the potential to cause major disasters in the ecological environment and human life [22]. As EMR is a sulfur-rich material (with an SO\({}_{3}\) content of approximately 17-25%), it can be considered similar to gypsum. Studies have shown that EMR can be combined with GBFS and clinker/Ca(OH)\({}_{2}\) to prepare cement-based cementitious materials, and its mechanical properties have been found to be superior to those of ordinary Portland cement (OPC) after 28 days of curing [23; 24]. According to the above, EMR holds potential as a building raw material, but its optimal performance is often realized when used in conjunction with alkaline raw materials. Therefore, to reduce carbon emissions in the cement industry and realize the utilization of industrial solid waste, this study utilized harmless modified EMR and CS to enhance the cementitious activity of GBFS through alkali-sulfur co-activation.