# Mechanical, Electrical and Fractural Characteristics of Carbon Nanomaterial-Added Cement Composites
## 2 Materials and Methods  
Cement-based composite materials were prepared at different mixing ratios to study the mechanical, electrical, and fracture characteristics of cement composites containing CNMs. The cement paste binder used in this study was made using ordinary Portland cement (OPC) and normal tap water. The CNT, CNF, and graphene used in this study were purchased from Beijing Daoking Co., Ltd. (Beijing, China), and the GNP was purchased from Timenano Co., Ltd. (Chengdu, China). The physical characteristics of the four CNMs (CNT, CNF, graphene, and GNP) employed in this investigation are consistent with those reported in a study conducted by [PERSON] et al., in 2020 [7]. The CNM composite mixture ratios and fabrication techniques adopted in this study are stated as follows: a group of composite samples was prepared using only cement and water, which were termed \"cement-only\". Cement-only samples were used to form a reference group. In total, four cement-only composite samples were fabricated. In addition to the cement-only samples, four types of composites, namely, CNT/cement, CNF/cement, graphene/cement, and GNP/cement, with four different mixing ratios were prepared. CNM/cement composites used CNM content ratios of 0.1%, 0.3%, 0.6%, and 1% by cement weight. Four replicate samples were prepared for each CNM ratio. Sixteen samples were fabricated for each type of CNM/cement composite. The mix proportions of the composite materials are listed in Table 1.  
The fabrication procedure is shown in Figure 1 and is explained as follows. First, each component of the cement composite, that is cement, water, and CNM, was weighed. After weighing all components, cement and CNM were poured into a steel container and thoroughly mixed for approximately three minutes. After three minutes, water was added, and then the mixture was mixed for another two minutes. After thorough mixing, the freshly prepared CNM/cement composites underwent a flow test in compliance with ASTM C230 [63]. After performing the flow test, superplasticizer (SP) was added as needed to maintain the fluidity within the range of 120-160 mm (corresponding to 20 to 60%). For samples that maintained fluidity within this range, SP was not added. After obtaining the \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Composite Type** & **CNM Ratio** & **SP * (g)** & **Water (g)** & **Cement (g)** & **W/C Ratio** & **CNM (g)** \\ \hline \multirow{4}{*}{CNT/cement} & 0.1 & 0 & & & & 2.2 \\  & 0.3 & 14 & & & & 6.5 \\  & 0.6 & 25 & & & & 13.0 \\  & 1 & 82.7 & & & & 21.7 \\ \hline \multirow{4}{*}{CNF/cement} & 0.1 & 0 & & & & 2.2 \\  & 0.3 & 0 & & & & 6.5 \\  & 0.6 & 1.8 & & & & 13.0 \\  & 1 & 7 & & & & 21.7 \\ \hline \multirow{4}{*}{Graphene/cement} & 0.1 & 0 & & & & 2.2 \\  & 0.3 & 0 & & & & 6.5 \\  & 0.6 & 5.7 & 541.4 & 2165.4 & 0.25 & 13.0 \\  & 1 & 20 & & & & 21.7 \\ \hline \multirow{4}{*}{GNP/cement} & 0.1 & 0 & & & & 2.2 \\  & 0.3 & 0 & & & & 6.5 \\ \cline{1-1}  & 0.6 & 0 & 541.4 & 2165.4 & 0.25 & 13.0 \\ \cline{1-1}  & 1 & 2.3 & & & & 21.7 \\ \hline \multirow{4}{*}{Cement only} & \multirow{4}{*}{0} & \multirow{4}{*}{541.4} & \multirow{4}{*}{2165.4} & \multirow{4}{*}{0.25} & \multirow{4}{*}{0} \\ \cline{1-1}  & & & & & & 21.7 \\ \hline \end{tabular}  
* Note that the W/C ratio refers only to the water-to-cement ratio and does not consider the superplasticizer (SP).  
\end{table} 
Table 1: Mix proportions. desired fluidity, the composite mixtures were poured into 40 mm \(\times\) 40 mm \(\times\) 160 mm steel molds. After the mold was filled, a mechanical vibrator was used for proper compaction. The sample was allowed to settle for 24-48 h at room temperature. After settling, the hardened composite samples were removed from the molds. Then, the composite samples were cured in tap water for 28 days. A novel method was used in an effort to distribute CNM in cement composites. The method was developed according to research conducted by [PERSON] and [PERSON], 2015 [PERSON] and [PERSON], 2015 [PERSON] and [PERSON] (2015 Nam).