# Experimental Study on Flexural Capacity of Corroded RC Slabs Reinforced with Basalt Fiber Textile
## 3 Experimental Results and Discussion
### Failure Patterns  
The control slabs exhibited a typical flexural mode of failure that was due to yielding of the tensile reinforcements followed by concrete crushing at the compression zone.  
All strengthened slabs failed in flexure after displaying flexural strength considerably higher compared to the corresponding control specimens, but the failure process was different from the control specimens. When the strengthened specimens were maintained within the elastic stage, the load-deflection relationship was linearly developed. Thereafter, the minor cracks propagated, increased and coalesced with the increase in the applied loads. Meanwhile, the fibers fractured gradually with the sound of cracking followed  
Figure 11: Relationship between flexural capacity and corrosion ratio.  
Figure 12: Effect of number of strengthening layers (**a**) moderate corrosion; (**b**) severe corrosion.  
by yielding of the tensile reinforcements. Subsequently, there was a loud snap and the strengthened layers damaged integrally, leading to a sudden load drop from the peak point. At the post-peak stage, the load almost remained constant while the width of flexural cracks and deflection of the slabs grew rapidly. Finally, the concrete in the compression zone was crushed and the specimens failed. The only exception was specimen M-P-5, which hardly had the post-peak stage because the strengthening layers and compressive concrete of that slab damaged almost simultaneously.  
The details visual mapping of flexural cracks was shown in Figure 8. The flexural crack pattern of BFRP-strengthened slabs was dominated by the main cracks across the bottom surface of the slabs. As for the BTRM-strengthened specimens, a series of transverse cracks were observed during the whole test. In this respect, the BTRM composites seemed to present better performance at distributing stresses during the cracking process than the BFRP composites.  
Four damage patterns of strengthening layers were observed in the strengthened slabs as shown in Figure 13. Strengthening layers of M-P-3, S-P-5, and S-M-5 failed due to fiber fracture at the mid-span region of the slabs (Figure 13a). The damage pattern for M-P-5 and S-P-3 was debonding of BFRP from the concrete surface accompanied with peeling off of the concrete cover (Figure 13b). However, the debonding of the BTRM composites of M-M-5 and S-M-3 occurred at the concrete-matrix interface (Figure 13c). In both debonding patterns, BFRP and BTRM composites, debonding initiated from the mid-span region and propagated toward the end of the slab. The BTRM composite of M-M-3 failed due to slippage of the fibers within the matrix accompanied by partial fracture of the fibers, at the maximum flexural moment region as shown in Figure 13d. Therefore, the load drop of M-M-3 was relatively gradual and smooth (refer to Figure 9).  
Figure 13: Damage patterns of specimen-strengthening layers: (**a**) fracture damage of strengthening layer; (**b**) debonding of BFRP layer (**c**) debonding of BTRM layer; (**d**) slippage damage of BTRM layer.