## 3 Test Results and Discussion
### Bond Strength  
The direct pull-out test conducted in this study consisted of testing and reporting the failure load, mode of failure, bond strength, and the load-slip relationship for each test. The bond strength, which is a critical factor in assessing the bond behaviour, is calculated using Equation (1), above. The failure load and the corresponding bond strength of the various test specimens are detailed in Table 4, below:  
From the bond test results, it is evident that the average bond strength of the steel-reinforced self-compacting geopolymer specimens is greater than that of the basalt FRP  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**SL.No**} & \multirow{2}{*}{\begin{tabular}{c} **Specimen** \\ **No** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Bar** \\ **Diameter,** \\ **d\({}_{\text{b}}\) **(mm)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Embedment** \\ **Length** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Max. Load** \\ **at Failure,** \\ **P\({}_{\text{max}}\) **(N)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Bond Stress,** \\ **\(\tau_{\text{max}}\) **(MPa)** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Average Bond** \\ **Stress,** \(\tau_{\text{max}}\) **(MPa)** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Standard** \\ **Error of Mean** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Mode of Failure** \\ **Failure** \\ \end{tabular} } \\ \hline
1 & 6-1-1 & 6 & 5 \(\text{d}_{\text{b}}\) & 1313.21 & 2.32 & & & Pull-out \\ \hline
2 & 6-1-2 & 6 & 5 \(\text{d}_{\text{b}}\) & 5849.67 & 10.34 * & 3.30  
reinforced specimens. It can be observed that at the same embedment length of 5 d\({}_{\text{b}}\), BFRP behaved like steel bar, reporting almost 72% of the bond strength of steel. The higher bond strength exhibited by steel bars can be attributed to the higher axial stiffness and ribbed surface of the steel bars in comparison to the basalt FRP bars [3]. In this study, the 6-mm BFRP bars reported a lower bond strength, where the bars pulled out earlier due to the greater ultimate tensile strength of the bars in comparison with the bonding force between the bars and the surrounding concrete, as reported in a study by [PERSON] et al. [28]. This observation confirms the outcomes from the 2018 study by [PERSON] et al., where the reported bond strength was 1 MPa [29]. This implies that in the case of deformed steel bars, the bonding resistance of concrete is governed by shear-based resistance, while it is friction-based for the basalt bars [29; 30].  
However, for the 10-mm BFRP bars, the trend was consistent with the widely reported literature, where an increase in the embedment length led to an uneven stress distribution, resulting in lower ultimate bond stress values [14; 28; 31; 32; 33; 34]. The relationship between bond stress and embedment length with various bar diameters of BFRP bars is summarized in Figures 9 and 10 below:  
The decreased bond strength reported for the basalt FRP bars can also be attributed to the relatively smooth surface of the bars when compared to the deformed steel bars.  
Figure 10: Average bond stress of 10-mm BFRP bars vs. embedment length.  
Figure 9: Average bond stress of 6-mm BFRP bars vs. embedment length.  
basalt FRP bars are a relatively new type of FRP bar whose material properties are still under investigation. Research on the bond performance of BFRP bars with various surface treatments--such as sand coating, helical wrapping, or ribbing with indentations--has been carried out by various researchers [2; 35; 36; 37; 38]. It has been found that providing sand coating increases the bond strength [35; 38]; however, the sand coating has been found to separate from the core of the bar under severe exposure, such as that in marine environments [39]. The future direction of the current study aims at assessing the properties of BFRP bars under marine exposure conditions; hence, BFRP bars without any surface treatment were chosen.