# Reactivity Assessment of Modified Ferro Silicate Slag by R\({}^{3}\) Method
## 5 Conclusions  
The presented work gives a deep insight into the reactivity of a novel SCM, namely a fumed secondary copper slag called MFS slag. Reactivity of the MFS slag was successfully assessed by the recently developed R\({}^{3}\) model technique. The R\({}^{3}\) model paste designed by RILEM for assessing the reactivity of the SCMs allows us to overcome the limitations of the traditional reactivity test methods with PC-based pastes. From the R\({}^{3}\) model analysis, it was found that MFS slag can be regarded as a pozzolanic SCM due to its reactive behavior and can be used as SCM to make concrete.  
The following can be stated as important findings from this work:  
1. Bound water analysis of the R\({}^{3}\) model paste showed that GGBFS and MFS slag possess a high amount of binder hydrates due to their latent hydraulic and pozzolanic behavior, respectively. These hydrates decomposed between 105 and 350 \({}^{\circ}\)C during the thermal treatment.
2. CH consumption studied by TGA analysis showed that MFS slag had similar pozzolanic properties as other traditional SCMs.
3. R\({}^{3}\) calorimetric analysis indicated that MFS slag provoked a cumulative heat release in the range between FA and GGBFS (although some of the heat release could be due to the presence of Zn). Inert filler of quartz showed almost no heat release with R\({}^{3}\) calorimetric analysis, corresponding with consumption of only a slight amount of CH found by TGA analysis.
4. XRD analysis of the R\({}^{3}\) model MFS slag indicated the participation of \"Fe\" in the hydration mechanism and the existence of Fe-AFm, next to other hydrated binder phases.  
One of the main research priorities in the future is to better understand the dissolution and role of ZnO and Fe\({}_{2}\)O\({}_{3}\) in the hydration mechanism of MFS slag, and the role of CaCO\({}_{3}\) in the formation of AFt/AFm phases for the R\({}^{3}\) model paste. In this respect, future experimental research such as Mossbauer and Raman spectroscopy analysis are needed to verify the participation of Fe\({}_{2}\)O\({}_{3}\) and ZnO in the hydration mechanism. Future research is also needed to verify the performance over long time scales, including complete durability assessment such as resistance to chloride and alkali silica reaction.  
Conceptualization: N.D.B., S.M., E.G., P.P.S.; methodology: P.P.S., N.D.B., S.M., E.G.; formal analysis and investigation: P.P.S.; writing--original draft preparation: P.P.S.; writing--review and editing: N.D.B., S.M., E.G.; funding acquisition: S.M., N.D.B., E.G.; resources: N.D.B., S.M.; supervision: [PERSON], N.D.B., E.G. All authors have read and agreed to the published version of the manuscript. This research was funded by the SIM MARES program (DUSC project), grant number HBC.2017.0607.  
Not applicable. Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to the SIM ICON Project Agreement DUSC (HBC.2017.0607), Contract ref. A18T1346.  
The authors would like to acknowledge the industrial partner Resourcefull for providing raw materials. The authors would also like to thank SCRiPTS and COMOC research groups, Department of Chemistry, Ghent University for assisting with the TGA and XRD measurements. The authors declare no conflict of interest.