## 2 Materials and Mix Designs
### Mix Design  
The GONF-cement paste was prepared by mixing OPC and water with the different percentages of GONFs (0.01-1 wt. %). For the comparison of different types of mix design, two different mix design methods were employed (Dry-mix and Wet-mix designs). Dry-mix design represents that the GONF powder is mixed with cement grains in a shear mixer prior to mixing with water. Wet-mix design represents that GONF powder is dissolved into water by sonication, and the GONF solution is then mixed with cement. For the dispersion of GONF powder in OPC powder (Dry-mix design), (1) one kilogram of OPC power is placed in a zip-lock plastic bag; (2) GONF power is spread on OPC and the bag is sealed; (3) The zip-lock plastic bag is rubbed with hands for a minute to apply shearing force and (4) one kilogram of GONF-mixed OPC is poured in the rest of OPC power for the mix and mixed with a portable mixer for a minute. For the dispersion of Wet-mix design, (1) the required amount of GONF powder is poured into one gallon of water; (2) the sonicator is placed in GONF-mixed water; and (3) the sonicator is operated for a minute prior to the mixing. The GONF was used as an additive in cement paste and the GONF content was varied from 0.1% to 1% with respect to the weight of OPC in the mix. For each mix design, three specimens were prepared for mechanical tests after curing. A weight ratio of water to cement of 50:100 (w/c 0.5) is used for the GONF-cement composite. Cubic specimens of GONF-cement composites (dimension of 50 mm \(\times\) 50 mm \(\times\) 50 mm) were prepared for compressive strength testing. The sample dimensions for flexural strength testing of cement paste was 50 mm \(\times\) 100 mm \(\times\) 25 mm. The samples were cured at 20 \({}^{\circ}\)C and 90% relative humidity until testing. Detailed mix proportioning of control and GONF-cement pastes are shown in Table 3. The specimen ID is denoted as P (cement paste), PD (GONF-combined paste with Dry-mix design) and PW (GONF-combined paste with Wet-mix design).  
For GONF-concrete, OPC, water, fine and coarse aggregates were mixed with different percentages of GONFs (0.01-0.1 wt. %). Detailed mix proportioning of concrete mix can be found from Table 3. Unlike GONF-combined paste mix (0.01-0.1 wt. % of GONF), GONF was added to concrete mix from 0.01 % to 0.1 wt. % since the optimum content of GONF was found as 0.05% for the improvement of GONF-combined paste. Moreover, only Dry-mix design was used for the concrete mix. To make GONF solution for Wet-mix, applying sonication is necessary. However, applying sonication to a large amount of water is ineffective as well as not practical for the concrete industry. Therefore, Wet-mix design may not be feasible for field construction. The specimen ID is referred as C (concrete) and CD (GONF-combined concrete with Dry-mix design).  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Specimen ID**} & **w/c** & **Water** & **Cement** & **GONF** & **Fine Agg.** & **Coarse Agg.** \\ \cline{2-7}  & **Ratio** & **(kg/m3)** & **(kg/m3)** & **(kg/m3)** & **(kg/m3)** & **(kg/m3)** \\ \hline P & 0.5 & 180 & 360 & - & - & - \\ PD0.01 & 0.5 & 180 & 360 & 0.036 & - & - \\ \hline \hline \end{tabular}
\end{table}
Table 3: Mix proportions of GONF-cement paste and concrete specimens (kg/m3).  
Figure 5: Gradation curves for coarse aggregates and ASTM C33 grading requirements for No. 57 aggregate.