## 4 Conclusions  
In this study, the effect on the fresh and mechanical properties as well as electrical conductivity of developed conductive FRCM containing carbon and steel fibers were compared and reviewed with PM. The results obtained from this study may be summarized as follows:  
1. Although the target flow value of the mixture containing PM and steel fibers was satisfied, it appeared that the flow value was significantly reduced in the case of the carbon fibers compared to PM due to some absorption of mixed water during mixing.  
Figure 14: EDS analysis results of the carbon and steel fibers captured at the fracture surface in CFRCM and SFRCM; (**a**) carbon fibers, and (**b**) steel fibers.  
2. The unit weight could be reduced by about 3% or more as the volume fraction of carbon fibers increased, and decreased by about 12% or more compared to PM. On the other hand, it was found that the change in the air contents were relatively insignificant regardless of the fiber volume fractions.
3. Both conductive CFRCM and SFRCM showed an overall increase in flexural strength compared to PM, and CFRCM had an effect of improving the flexural strength of about 0.3 to 43.1%, whereas SFRCM had a greater effect on improving the flexural strength of about 40.1 to 96.0%.
4. The compressive strength of developed conductive SFRCM was generally higher than that of PM, whereas in the case of developed conductive CFRCM, the decreasing tendency was larger as the volume fraction of carbon fibers increased.
5. The developed conductive CFRCM and SFRCM were clearly different in terms of electrical conductivity enhancement. In the case of CFRCM, the electrical conductivity increased significantly as the fiber dosages increased. However, incorporation of carbon fibers beyond the percolation threshold (i.e., 0.4%) does not develop conductivity because the conductive path is already formed.
6. The results of SEM/EDS analysis showed that in the case of SFRCM containing steel fibers, the interfacial adhesion force was superior to that of CFRCM containing carbon fibers because crystals of hydration product of cement were formed on the fiber surface and C-S-H gels were distributed within the cement mortar.  
Conceptualization, [PERSON]-[PERSON] and [PERSON]-[PERSON]; methodology, [PERSON]-[PERSON] and [PERSON]-[PERSON]; validation, [PERSON]-H.H. and [PERSON]-[PERSON]; formal analysis, [PERSON]-M.J. and [PERSON]-G.P.; investigation, [PERSON]-G.P., D.-J.S. and [PERSON]-J.L.; writing--original draft preparation, [PERSON]-M.J. and [PERSON]-[PERSON]; writing--review and editing, [PERSON]-H.H. and D.-J.S.; visualization, [PERSON]-G.P., D.-J.S. and [PERSON]-Y.L.; supervision, G.-H.H.; project administration, G.-H.H.; funding acquisition, G.-H.H. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Basic Science Research Program through the National Research Foundation of Korea (NRF) of the Ministry of Education, Republic of Korea (Grant no. NRF-2018R1A6A1A03025542).  
Not applicable.  
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant no. NRF-2018R1A6A1A03025542).  
The authors declare that there is no conflict of interest.