## 3 Results and Discussion  
### Sample Properties  
Figure 3 shows the results of the flow table and compressive and flexural strength tests. The average flow diameter of WS60 was 24% smaller than that of WS0, indicating that the addition of a higher volume of slag could affect the fluidity of fresh wollastonite mortar mixes by adsorbing more free water onto their angular surfaces. However, the flow of wollastonite improved in the presence of 20% slag, which may be due to the higher presence of wollastonite that used free water available in the fresh matrix. This finding recommends the use of superplasticizers during the increasing use of slag in wollastonite mixtures to avoid workability issues. [PERSON], et al. [37] found volume expansion problems in cement mixes containing EAF slag due to free CaO and a decrease in workability due to water absorption. In this study, the NaOH solution was used in the preparation of fresh mortar samples. This alkaline solution breaks the weak bonds of SiO\({}_{2}\) in EAF slag, thus releasing metasilicate anions. These silicate anions are easily involved in the reaction with CaO of raw materials under normal conditions [15]. The average compressive strength of the WS0, WS20, WS40, and WS60 samples was determined to be 18, 19, 21, and 16 MPa, while their flexural strength was 11.2, 12.3, 10.8, and 7.7 MPa, respectively. The compressive and flexural strengths of WS20 were found to be 6% and 10% greater than those of WS0 (i.e., reference sample). There is a decrease in these strengths of mortar samples by up to 11% and 31% due to the greater replacement of wollastonite with EAF slag. There is no significant change in the development of the strength of the wollastonite mixes when the addition of EAF slag was limited to 50%. In particular, the wollastonite matrices mixed with 20% EAF slag exhibited the highest mechanical performance. Coarse EAF slag particles were used as an aggregate [25], and the proposed reason for the observed increase in strength is that slag particles are porous, allowing the cement paste to penetrate the slag particles, resulting in an interlocked system that can lead to higher strength. In this study, the drop in compressive strength of WS60 was attributed to multiple reasons. First, if the interlocking effect of combining wollastonite and slag as binders can contribute to an increase in compressive strength, it is possible that a mortar mix containing significantly less wollastonite than EAF slag will not be able to bind effectively, leading  
Figure 3: Results of the flow table and compressive and flexural strength tests. to a drastic decrease in strength. A study suggests that smaller particle sizes, including the EAF slag size, may be associated with more efficient carbonation, potentially affecting the formation of CSH and CaCO\({}_{3}\) with crystalline morphologies [22]. It is also observed that cement mixes containing EAF slag tend to be more susceptible to water permeation, suggesting that they have a higher volume of spaces, which is associated with a decrease in strength [11]. The WS60 mix was largely composed of EAF slag and is therefore much more porous and less dense than other mixes due to the coarser texture and larger particle size of the binder material used. Although the WS40 mix appears to have an ideal ratio of EAF slag to wollastonite to allow optimal interlocking and minimal void space, the WS60 mix lacks homogeneity and, therefore, does not have enough wollastonite to interlock and is significantly more porous. The high Fe\({}_{2}\)O\({}_{3}\) content in EAF slag has also been found to be associated with a decrease in strength when used as a binder [28]. However, when the Fe\({}_{2}\)O\({}_{3}\) content is reduced, it is observed that the compressive strength tends to perform better [22]. Therefore, it is possible that the WS40 mix has a lower Fe\({}_{2}\)O\({}_{3}\) content compared with WS60, which contains less wollastonite, more EAF slag, and therefore more Fe\({}_{2}\)O\({}_{3}\).