## 3 Experimental Results
### Electrical Resistance Testing
Figure 12 shows the variation in the electrical resistance of the composites after 28 d of curing according to the parameters. Figure 12a shows the electrical resistance of the composites with 0.125 wt% MWCNT. The electrical resistances of cement paste were 7.8 k\(\Omega\) for CP-0.125-28D-X and 15.2 k\(\Omega\) for CP-0.5-28D-O, and the difference owing to the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Specimen Name** & **Composite Type** & **Curing Days** & **Concentration (wt\%)** & **Resistance (K\(\Omega\))** \\ \hline CP-0.125-7D-X & & & & 3.4 \\ CP-0.125-7D-O & & & & 10.2 \\ CP-0.25-7D-X & & & & 1.6 \\ CP-0.25-7D-O & & & & 2.5 \\ CP-0.5-7D-O & & & & 0.4 \\ CP-0.125-28D-X & & & & 1.1 \\ CP-0.125-28D-X & & & & 7.8 \\ CP-0.125-28D-O & & & & 15.2 \\ CP-0.25-28D-X & & & & 3.5 \\ CP-0.25-28D-O & & & & 5.1 \\ CP-0.5-28D-X & & & & 1.8 \\ CP-0.5-28D-O & & & & 3.0 \\ \hline M-0.125-7D-X & & & & 62.0 \\ M-0.125-7D-O & & & & 90.2 \\ M-0.25-7D-X & & & & 21.4 \\ M-0.25-7D-O & & & & 39.2 \\ M-0.5-7D-X & & & & 7.6 \\ M-0.5-7D-O & & & & 20.5 \\ M-0.125-28D-X & & & & 75.7 \\ M-0.125-28D-O & & & & 110.8 \\ M-0.25-28D-X & & & & 41.5 \\ M-0.25-28D-O & & & & 62.8 \\ M-0.5-28D-X & & & & 18.6 \\ M-0.5-28D-O & & & & 36.2 \\ \hline Co-0.125-7D-X & & & & 81.0 \\ Co-0.125-7D-O & & & & 118.0 \\ Co-0.25-7D-X & & & & 46.0 \\ Co-0.25-7D-O & & & & 71.1 \\ Co-0.5-7D-X & & & & 35.8 \\ Co-0.5-7D-O & & & & 50.5 \\ Co-0.125-28D-X & & & & 100.5 \\ Co-0.125-28D-O & & & & 142.8 \\ Co-0.25-28D-X & & & & 51.6 \\ Co-0.25-28D-O & & & & 79.0 \\ Co-0.5-28D-X & & & & 41.2 \\ Co-0.5-28D-O & & & & 58.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Electrical resistance results for the specimens. Figure 11: Electrical resistance at 7 d of curing: (**a**) 0.125 wt%, (**b**) 0.25 wt%, and (**c**) 0.5 wt%. occurrence of damage was 7.4 k\(\Omega\). The electrical resistances of the mortar were 75.7 k\(\Omega\) for M-0.125-28D-X and 110.8 k\(\Omega\) for M-0.125-28D-O, which suggests a difference owing to the damage of 35.1 k\(\Omega\). The electrical resistance of concrete was 100.5 k\(\Omega\) for Co-0.125-28D-X and 140.8 k\(\Omega\) for Co-0.125-28D-O, which suggests that the difference owing to such damage was 40.3 k\(\Omega\), which was 3.3-k\(\Omega\) higher than that for 7 d of curing. The electrical resistances of the cement paste, mortar, and concrete with 0.25 wt% MWCNT are shown in Figure 12b. The electrical resistance of the composites without damage was 3.5 k\(\Omega\) for the cement paste, which was 2.2-times higher than that of the composites after 7 curing days, and 41.5 k\(\Omega\) for mortar, which was 1.9-times higher than that of the composite cured for 7 d. The electrical resistance of the concrete was 51.6 k\(\Omega\), which was the highest among the composites with 0.25 wt% MWCNT and was 1.1-times higher than that of 7 curing days. The electrical resistance of composites with damage was 5.1 k\(\Omega\) for cement paste, which was 1.6-k\(\Omega\) higher than that for the composite without damage, and 62.8 k\(\Omega\) for mortar, which was 21.3-k\(\Omega\) higher than that for the composite without damage. The electrical resistance of concrete was 79.0 k\(\Omega\), and the difference in electrical resistance owing to the presence of damage was 27.4 k\(\Omega\). The electrical resistances of the composites with 0.5 wt% MWCNT were 1.8 k\(\Omega\) for CP-0.5-28D-X and 3.0 k\(\Omega\) for CP-0.5-28D-O. For mortar, they were 18.6 k\(\Omega\) for M-0.5-28D-X and 36.2 k\(\Omega\) for M-0.5-28D-O. For concrete, they were 41.2 K\(\Omega\) for Co-0.5-28D-X and 58.4 k\(\Omega\) for Co-0.5-28D-O (Figure 12c). When compared with the 7 d of curing, the electrical resistance increased by up to 4.5 times for cement paste, by up to 2.4 times for mortar, and by up to 1.2 times for concrete. The difference in electrical resistance owing to the presence of damage was 1.2 k\(\Omega\) for cement paste, 17.6 k\(\Omega\) for mortar, and 17.2 k\(\Omega\) for concrete.