## 3 Test Results and Discussion
### Load-Slip Relationship  
The slip of basalt FRP bars from the SCGC blocks was recorded throughout the test. The load-slip relationship for 6-mm bars of 5 d\({}_{\rm b}\), 10 d\({}_{\rm b}\), and 15 d\({}_{\rm b}\) is plotted in Figure 18 below:  
Figure 17: Crack on the top surface of the 15 d\({}_{\rm b}\) pull-out specimens. Figure 18: Load–slip relationship of specimens with 6-mm BFRP bars of 5 d\({}_{\rm b}\),10 d\({}_{\rm b}\), and 15 d\({}_{\rm b}\) embedment lengths. The specimens of 6-mm diameter of 5 \(\mathrm{d_{b}}\) and 10 \(\mathrm{d_{b}}\) embedment lengths pulled out from the concrete at early loading stages, even before reaching the peak stresses of the bar. When a larger embedment length of 15 \(\mathrm{d_{b}}\) was used (Figure 22), the bond strength of the specimens showed an increase similar to that reported by [PERSON] and [PERSON] in their study on BFRP bars in conventional concrete [16]. While observing the pull-out failure of 10-mm BFRP bars it was seen that the load taken by the 10-mm BFRP bars was higher than their 6-mm counterparts, and the bond strength was higher for smaller embedment lengths of 5 \(\mathrm{d_{b}}\), as shown in the load-slip plot in Figure 19.  
However, as the embedment length increased to 10 \(\mathrm{d_{b}}\) and 15 \(\mathrm{d_{b}}\), the ultimate failure load increased; however, the bond strength was smaller due to the non-uniform distribution of stresses over larger lengths of bond, leading to loss of grip from the concrete face and pull-out of bars. It is also of interest to note that in the longest embedment length (15 \(\mathrm{d_{b}}\)) of BFRP bar, the bar pulled out before peak load, and the loading continued until splitting cracks were observed on the pull-out specimens. The load-slip plot for the steel bars is shown in Figure 20 below, and the failure pattern was of pull-out type for all three specimens of the 5 \(\mathrm{d_{b}}\) embedment length. However, for the first specimen (S-10-1), erroneous values were reported due to faulty running of the test machine, and these values were not considered for bond strength calculation. Figure 19: Load–slip relationship of specimens with 10-mm BFRP bars of 5 \(\mathrm{d_{b}}\),10 \(\mathrm{d_{b}}\), and 15 \(\mathrm{d_{b}}\) embedment lengths. Figure 20: Load–slip relationship of the 10-mm, 5 \(\mathrm{d_{b}}\) steel specimens. The load-slip relationship comparing the performance of 6-mm BFRP bars of various embedment lengths (5 d\({}_{\text{b}}\), 10 d\({}_{\text{b}}\), and 15 d\({}_{\text{b}}\)) against the performance of steel bars is also plotted below in Figure 21. In comparison to the steel bars, the BFRP bars of smaller diameter (i.e., 6 mm) could not perform well under pull-out test loads. Due to their smaller size and lower bond capacity, the bars pulled out of the concrete earlier, even before reaching the peak loads. The embedment length variations also did not make a difference in the bond strength capacities when compared to the steel bars, which performed well against the smaller diameter basalt FRP bars. Moreover, the load-slip relationship comparing the performance of 10-mm BFRP bars of various embedment lengths (5 d\({}_{\text{b}}\), 10 d\({}_{\text{b}}\), and 15 d\({}_{\text{b}}\)) against the performance of steel bars is also plotted below in Figure 22.  
The peak loads of the 10-mm steel bars and 10-mm BFRP bars are in a similar range, confirming the suitability of BFRP bars as reinforcement materials, as can be seen from  
Figure 21: Load–slip relationship of the 6-mm BFRP and steel bars. Figure 22: Load–slip relationship of the 10-mm BFRP and steel bars. the comparison plot in Figure 22. This indicates that the 10-mm bars of BFRP give similar pull-out performance when compared to steel bars of same diameter, showing promising potential for the use of Basalt FRP as an alternative for the conventional steel reinforcing bar.