# Mechanical, Electrical and Fractural Characteristics of Carbon Nanomaterial-Added Cement Composites
## 4 Conclusions  
In this study, CNF/cement, GNP/cement, CNT/cement, and graphene/cement composites with various CNM content ratios were fabricated, and their mechanical (compressive strength, and flexural strength), fractural (fracture energy, fracture toughness, and maximum flexural displacement) and electrical characteristics were examined. The mechanical properties were further analyzed by evaluating their porosity characteristics. The following conclusions were drawn from this study. * Compared to all other CNM-added cement composites, 0.3% CNT-added cement composites showed the maximum increase in compressive strength. For the CNF-added cement composite, the current study concluded that compressive strength increased with an increase in the CNF content ratio. GNP- and graphene-added cement composites demonstrated that adding a small dosage of 0.1% is ideal for improving the compressive strength. * Similar to compressive strength results, cement composites with 1.0% CNF ratio exhibited the highest flexural strength among all CNM-added cement composites. Regarding GNP or graphene-added cement composites, the maximum flexural strength was achieved with a 1.0% dosage. The flexural strength of cement composites improved as the CNT dosage increases up to 0.6%. * The fracture characteristics of the CNM/composites underlined that graphene-added cement composites attained the maximum fracture energy. Accordingly, fracture toughness was improved with a 1.0% content ratio compared to that of other CNM-added composites. Similarly, CNF- and GNP-added cement composites showed maximum improvement in fractural characteristics at 1.0% dosage. The CNT-addedcement composites exhibited maximum fractural characteristics at a CNT dosage of 0.6%. * A CNT content ratio between 0.3% and 0.6% can be the optimal ratio for improving cement composites' mechanical and fractural characteristics. When CNT content was further increased to 1.0%, a sharp decrease in mechanical properties and fractural characteristics was observed. This phenomenon was due to the non-uniform dispersion of CNT in the cement matrix, which created agglomerations of CNT, thereby decreasing the mechanical properties and flexural characteristics. * The porosity results of CNF/cement composites showed an inverse relationship with all mechanical properties and flexural characteristics. In the GNP/cement, CNT/cement, and graphene/cement composites, flexural strength, fracture toughness, and fracture energy improved as porosity decreased. However, an increase in compressive strength did not exhibit a clear relationship with the porosity. Besides porosity, factors such as the aspect ratio of CNMs and the degree of dispersion of CNMs in cement composites require further investigation. * Based on electrical conductivity test results, the CNF/cement composites showed a percolation threshold ranging from 0.3% to 1.0%, and CNT/cement showed a percolation threshold ranging from 0.1% to 0.3%. Meanwhile, the GNP and graphene showed an insignificant change in electrical conductivity with an increased content ratio, and exhibited no percolation threshold phenomena. Conceptualization, I-W.N. and J.Y. ; methodology, I-W.N. and M.B. ; formal analysis, M.B. and I-W.N. ; investigation, M.B. ; data curation, M.B. and I-W.N. ; writing--original draft preparation, M.B. and I-W.N. ; writing--review and editing, I-W.N. and M.B. ; visualization, I-W.N. and M.B. ; supervision, I-W.N. and J.Y. ; project administration, I-W.N. and J.Y. ; funding acquisition, I-W.N. and J.Y. All authors have read and agreed to the published version of the manuscript. This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry, and Energy (MOTIE) of the Republic of Korea (Grant Number 20214000000010). This work was also supported by the Korea Hydro & Nuclear Power Co. (2025). Not applicable. The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.