## 2 Materials and Experiments
### Test Methods  
The setting time of the CNT paste was measured in a constant temperature and humidity chamber (23 \({}^{\circ}\)C and 50%) using a Vicat device in accordance with ASTM C191 [39]. The compressive strength of the CNT paste was measured at 28 days in accordance with ISO 679 [40]. For each mixture in Table 2, three specimens were fabricated using a 40 \(\times\) 40 \(\times\) 160 mm metal mold. The paste specimens were cured in a constant temperature and humidity chamber at 20 \(\pm\) 1 \({}^{\circ}\)C and a relative humidity of 90% or higher for 24 h. They were then removed from the mold and cured in a water tank at 20 \(\pm\) 1 \({}^{\circ}\)C until 28 days of age. Each specimen was split into two before measuring the compressive strength. The compressive strengths of six specimens were measured, and the average value was used. For the CNT paste, the heat flow of hydration and cumulative heat were measured using a TAM Air isothermal calorimeter in the same way as in the experiment conducted by [PERSON] and [PERSON] [41]. The TAM Air 8-channel standard volumetric calorimeter operates in the mW range and consists of an 8-channel twin-type calorimeter block and a data acquisition system. After each mixture was homogeneously mixed, approximately 4 g of paste was placed in a 20 mL glass ampoule and the weight was measured. The glass ampoule was installed in a calorimeter maintained at 23 \({}^{\circ}\)C and measured for 48 h. Figure 4 shows the TAM Air isothermal calorimeter used in this study. The autogenous shrinkage of CNT-reinforced cement composites was measured using a gauge embedded in the center of the specimen, which was placed in a 50 \(\times\) 50 \(\times\) 300 mm beam mold sealed with Teflon and polyester sheets, as shown in Figure 5. Three specimens were used to measure autogenous shrinkage for each variable. This test method was similar to that reported by [PERSON] et al. [42] and [PERSON] et al. [43]. The PMFL-series embedded strain gauges with a length of 60 mm and a diameter of 4 mm (Tokyo Sokki Kenkyujo Co., Ltd., Japan), showing the applicability in measuring the autogenous shrinkage inside CNT-reinforced cement composites, were pre-located inside the mold in this test. Teflon sheets were used inside the mold to minimize the stress that may occur during the early hardening process. In addition, buffer sponges were installed at both ends of the mold to minimize the restriction of the specimen at both ends. The top surface of the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Mixture** & **Water** & **Cement** & **Fly Ash** & **CNT** & **SP (1)** \\
**Name** & **(kg/m3)** & **(kg/m3)** & **(kg/m3)** & **(wt.\% of Binder)** & **(kg/m3)** \\ \hline CRC00 & 202 & 720 & 144 & 0.0 & 1.44 \\ CRC01 & 202 & 720 & 144 & 0.1 & 1.44 \\ CRC03 & 202 & 720 & 144 & 0.3 & 1.44 \\ CRC05 & 202 & 720 & 144 & 0.5 & 1.44 \\ \hline \hline \end{tabular} \({}^{()}\) polycarboxylate-based superplasticizer  
\end{table} 
Table 2: Mixture proportions of CNT-reinforced cementitious composites. Figure 4: TAM Air isothermal calorimeter. specimen was sealed using aluminum foil tape to prevent moisture evaporation. In this test, autogenous shrinkage was measured while the specimen was placed inside the mold without demolding. Autogenous shrinkage was measured in a constant temperature and humidity chamber at a temperature of 23 \(\pm\) 2 \({}^{\circ}\)C and a relative humidity of 60 \(\pm\) 10% every 5 min using a data logger. The autogenous shrinkage result was calculated based on the final setting time (See Table 3). The relative humidity inside the CNT-reinforced cementitious composites was measured using the setup shown in Figure 6. Approximately two-thirds of the disposable cylindrical sample cup (diameter of 45 mm and height of 40 mm) was filled with the specimen to be measured. A temperature humidity probe (HC2-AW-USB, Switzerland, Rotronic AG) was then fixed on top of the sample holder containing the sample cup.