## 4 Conclusions  
This study compared the performance of wollastonite-based mortar mixes containing 0-60% EAF slag. NaOH solution was used in their preparation, and the hydroxyl species broke the weak bonds of SiO\({}_{2}\) in the EAF slag, thus releasing metasilicate anions. These silicate anions are involved in the reaction with the CaO of wollastonite under normal conditions. It was observed that the wollastonite-based mortar sample containing 40% slag had the highest compressive strength, while the mixture containing 60% slag had the lowest compressive strength. This disparity in strength levels may be attributed to the formation of a high crystalline CSH content in the WS40, a severe lack of homogeneity in the WS60, and the interactions between EAF slag and wollastonite as binders. Despite having the lowest compressive strength, the mix containing 60% slag had the highest amount of CaCO\({}_{3}\) present, suggesting that CaCO\({}_{3}\) does not play a significant role in the development of the strength of EAF slag cements when sample homogeneity cannot be achieved. The level of compressive strength observed in the WS40 is a very promising sign for the use of EAF slag as a supplementary binder in the manufacturing of commercial cement. The use  
\begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Sample** & **WS0** & **WS20** & **WS40** & **WS60** \\ \hline Total weight loss (\%) & 5.6 & 5.4 & 9 & 9.7 \\ Weight loss due to CSH dehydroxylation 30–260 \({}^{\circ}\)C (\%) & 0.5 & 0.4 & 1.1 & 0.8 \\ Weight loss due to aragonite decomposition 650–750 \({}^{\circ}\)C (\%) & 2.6 & 2.6 & 1.7 & 3.3 \\ Weight loss due to calcite decomposition 750–1000 \({}^{\circ}\)C (\%) & 1 & 1.2 & 4.3 & 4.3 \\ Gel pore volume \(\sim\)10 nm (\%) & 18 & 0 & 42 & 4 \\ Capillary pore volume \(\sim\)10–100 nm (\%) & 56 & 48 & 11 & 71 \\ Macropore volume \(\sim\)100 nm (\%) & 26 & 52 & 47 & 25 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Microstructural properties of the wollastonite matrices interpreted from the TGA and MIP information.  
of this slag in the wollastonite matrix reduced the formation of pores by up to 76%. The use of EAF slag would be environmentally and economically sustainable; when used in combination with alkali activation and wollastonite, EAF slag appears to be usable even when untreated. This is likely related to the presence of crystalline CSH in wollastonite and slag blends because crystalline CSH is associated with increased stability in cementitious materials. The use of EAF slag in this context promotes the sequestration of CO\({}_{2}\), as well as the diversion of industrial waste from landfills.  
Conceptualization, methodology, validation, formal analysis, investigation, data curation, and writing--original draft preparation--M.M. and S.K.; resources--A.C.; supervision, writing--review and editing--L.S. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Narodowa Agencja Wymiany Akademickiej (NAWA), grant number BPN/ULM/2021/1/00120.  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.