## 4 Results and Discussion  
### Characterization of GONF  
Carbon based nanomaterials are unique with respect to their superior properties, which include, but not limited to, high tensile strength and elastic modulus, high surface area and electrical conductivity [1,11]. Mechanical and physical properties of the GONF used in this study were characterized with atomic force microscopy (AFM) and BET sorbtometery. Table 4 shows the comparison of OPC and GONF. It is known that mechanical properties (elastic modulus and tensile strength) of GONF are higher than steel [1,11]. Moreover, GONF is an ultra-fine material according to surface area in Table 4.  
In addition, carbon based nanomaterials have the diversity in their morphologies from one- to three-dimension. The surface morphology of GONF was investigated with scanning electron  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Properties** & **OPC** & **GONF** & **Test Methods and Device** \\ \hline Elastic modulus & - & 1 TPa & Atomic Force Microscope (AFM) \\ Tensile Strength & - & 130 GPa & AFM \\ Specific gravity (OD) & 3.15 & 1.91 & ASTM C127 [26], C128 [27] \\ Surface area & 33.10 m\({}^{2}\)/g & 204 m\({}^{2}\)/g & BET Sortpotometry \\ \hline \hline \end{tabular}
\end{table}
Table 4: Basic physical properties of materials, standard test methods and devise.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Specimen ID**} & **w/c** & **Water** & **Cement** & **GONF** & **Fine Agg.** & **Coarse Agg.** \\ \cline{2-6}  & **Ratio** & **(kg/m\({}^{3}\))** & **(kg/m\({}^{3}\))** & **(kg/m\({}^{3}\))** & **(kg/m\({}^{3}\))** & **(kg/m\({}^{3}\))** \\ \hline PD0.05 & 0.5 & 180 & 360 & 0.18 & - & - \\ PD0.1 & 0.5 & 180 & 360 & 0.36 & - & - \\ PD0.5 & 0.5 & 180 & 360 & 0.36 & - & - \\ PD1 & 0.5 & 180 & 360 & 3.6 & - & - \\ PW0.01 & 0.5 & 180 & 360 & 0.036 & - & - \\ PW0.05 & 0.5 & 180 & 360 & 0.18 & - & - \\ PW0.1 & 0.5 & 180 & 360 & 0.36 & - & - \\ PW0.5 & 0.5 & 180 & 360 & 0.36 & - & - \\ PW1 & 0.5 & 180 & 360 & 3.6 & - & - \\ C & 0.5 & 180 & 360 & - & 761 & 949 \\ CD0.01 & 0.5 & 180 & 360 & 0.036 & 761 & 949 \\ CD0.02 & 0.5 & 180 & 360 & 0.072 & 761 & 949 \\ CD0.03 & 0.5 & 180 & 360 & 0.108 & 761 & 949 \\ CD0.04 & 0.5 & 180 & 360 & 0.144 & 761 & 949 \\ CD0.05 & 0.5 & 180 & 360 & 0.18 & 761 & 949 \\ CD0.1 & 0.5 & 180 & 360 & 0.36 & 761 & 949 \\ \hline \hline \end{tabular}
\end{table}
Table 3: _Cont._microscopy (SEM). SEM image of GONF which used in this study is presented in Figure 6 (see Figure 6c [16]) as compared with other carbon-based nanomaterials such as carbon nanofiber (CNF, Figure 6a [28]), graphene (Figure 6b [29]) and carbon nanotube (CNT, Figure 6d [30]). As can be seen in Figure 6, CNF, graphene and CNT appear in one-, two- and three- dimension morphologies. Each material has its own merit with their morphologies. As shown in Figure 6c, GONF is a wrinkled layer due to intercalated functional oxygen groups on the surface of graphene (see Table 2). It is found that a nominal particle size diameter of GONF is 500 nm with 90% of the particle sizes below 800 nm in diameter. The particle size of GONF can be tailored based on the starting material which is graphite and the mechanochemical processing conditions.