## 3 Results and Discussions
### Tensile Strength
It is worth mentioning that the relationship between the tensile strength and compressive strength of GPC is significantly influenced by several factors, i.e., type of source materials, chemical composition of the source materials, curing techniques, type of alkaline activators, and composition of activating solution. Considering the mixing procedure, curing method, testing age, and chemical composition of the source materials were similar for [PERSON] and [PERSON] (2013), [PERSON] et al. (2007), and the present study, the variation in the predicted and the measured values can be due to the difference in composition of the activating solution and the mix proportions. [PERSON] and [PERSON] (2013) used the AAS content as 56% of the total binder and NaOH solution with 4 M and 6 M molarity, whereas, in the present study, AAS contents were 40% and 35% of the total binder with molarity of NaOH solution as 10 M, 12 M, and 14 M. [PERSON] et al. (2007) used sodium silicate and potassium hydroxide to prepare the AAS. The sodium silicate and potassium hydroxide were mixed in a predetermined ratio of 1.5. However, in the present study, sodium silicate and sodium hydroxide were used to prepare the activating solution with their ratio as 2, 2.5, and 3.0. These variations might have resulted in different correlations for predicting the values of splitting tensile strengths. Nevertheless, the present study can be considered as an effort to propose a  
Figure 11: The influence of mix design variables on tensile strength of FS-GPC at the age of 28 days. relatively more suitable empirical relationship (Equation (6)), based on the existing data and the observations from the present study, for predicting the splitting tensile strength of ambient cured FS-GPC. \[f_{ct}=0.40\;(f_{c})^{1/2} \tag{6}\]  
where, \(f_{ct}=\) mean split tensile strength (MPa), and \(f_{c}\) = average compressive strength measured on cubes (MPa). Figure 12 shows the comparison of the test and estimated values of indirect tensile strength of GPC mixes specimens at the age of 28 days. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Mix ID**} & \multirow{2}{*}{**Compressive Strength,\(f_{cm}\) (MPa)**} & \multicolumn{5}{c}{**Tensile Strength,\(f_{ct}\) (MPa)**} \\ \cline{3-7}  & & **Test** & **[PERSON] \& [PERSON]** & **[PERSON] et al.** & **Test/[PERSON] \& [PERSON]** & **Test/[PERSON] et al.** \\ \hline A1-S10 & 20.0 & 1.9 & 2.0 & 2.1 & 0.94 & 0.89 \\ A2-S20 & 40.0 & 2.5 & 2.8 & 3.0 & 0.88 & 0.82 \\ A3-S30 & 54.0 & 2.9 & 3.3 & 3.5 & 0.88 & 0.82 \\ A4-S50 & 65.0 & 3.4 & 3.6 & 3.9 & 0.94 & 0.88 \\ B1-S20 & 48.0 & 2.8 & 3.1 & 3.3 & 0.90 & 0.84 \\ B2-S30 & 63.0 & 3.3 & 3.6 & 3.8 & 0.92 & 0.87 \\ B3-S20 & 53.0 & 2.9 & 3.3 & 3.5 & 0.89 & 0.83 \\ B4-S30 & 69.0 & 3.5 & 3.7 & 4.0 & 0.94 & 0.88 \\ C1-S10 & 26.0 & 2.3 & 2.3 & 2.4 & 1.00 & 0.94 \\ C2-S20 & 46.0 & 3.1 & 3.1 & 3.3 & 1.02 & 0.95 \\ C3-S30 & 59.0 & 3.3 & 3.5 & 3.7 & 0.95 & 0.90 \\ C4-S50 & 69.0 & 3.7 & 3.7 & 4.0 & 0.99 & 0.93 \\ D1-S20 & 46.0 & 2.9 & 3.1 & 3.3 & 0.95 & 0.89 \\ D2-S30 & 63.0 & 3.3 & 3.6 & 3.8 & 0.92 & 0.87 \\ D3-S20 & 37.0 & 2.5 & 2.7 & 2.9 & 0.91 & 0.86 \\ D4-S30 & 49.0 & 2.9 & 3.2 & 3.4 & 0.92 & 0.86 \\ E1-S10 & 17.0 & 1.7 & 1.9 & 2.0 & 0.92 & 0.86 \\ E2-S20 & 36.0 & 2.2 & 2.7 & 2.9 & 0.81 & 0.76 \\ E3-S30 & 51.0 & 2.7 & 3.2 & 3.4 & 0.84 & 0.79 \\ E4-S50 & 63.0 & 3.1 & 3.6 & 3.8 & 0.87 & 0.81 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The measured and predicted values of indirect tensile strength. Figure 12: The comparison of the test and estimated values of indirect tensile strength of GPC mixes specimens at the age of 28 days.