Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Analysis of variance (ANOVA) between bond strength results of CFRP and GFRP bars
| Concrete mix | Significance level (%) |
| C1 | 11.2 |
| C2 | 3.9 |
| C3 | 29.7 |
| S1 | 8.3 |
Mechanical characteristics of concrete mixes (MPa)
| Symbol | Compressive str. | Splitting tensile str. | ||
|---|---|---|---|---|
| Avg. | St.D. | Avg. | St.D. | |
| C1 | 39.14 | 1.26 | 2.91 | 0.36 |
| C2 | 48.80 | 1.10 | 3.40 | 0.33 |
| C3 | 54.21 | 1.50 | 3.72 | 0.19 |
| S1 | 67.16 | 3.57 | 4.13 | 0.08 |
Pull-out test results for Series 2
| Symbol | Bond strength | Loaded end slip | Free end slip | Bond stiffness | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| τb,max | Avg. | St.D. | C.O.V. | Slip a | Avg. | St.D. | C.O.V. | Slip a | Avg. | St.D. | C.O.V. | Avg. | ||
| (MPa) | (MPa) | (MPa) | (%) | (mm) | (mm) | (mm) | (%) | (mm) | (mm) | (mm) | (%) | (N/mm3) | ||
| Sand coated | 1 | 23.24 | 23.01 | 0.57 | 2.5 | 0.718 | 0.638 | 0.088 | 13.7 | 0.266 | 0.247 | 0.024 | 9.8 | 36.05 |
| 2 | 22.36 | 0.545 | 0.256 | |||||||||||
| 3 | 23.43 | 0.652 | 0.220 | |||||||||||
| Indented type | 1 | 20.02 | 18.91 | 1.17 | 6.2 | 0.581 | 0.606 | 0.148 | 24.4 | 0.317 | 0.319 | 0.068 | 21.3 | 31.19 |
| 2 | 17.69 | 0.473 | 0.252 | |||||||||||
| 3 | 19.03 | 0.765 | 0.388 | |||||||||||
| Indented type 2 | 1 | 11.21 | 12.25 | 1.29 | 10.5 | 1.138 | 1.198 | 0.103 | 8.6 | 0.957 | 0.917 | 0.069 | 7.5 | 10.23 |
| 2 | 11.84 | 1.138 | 0.957 | |||||||||||
| 3 | 13.69 | 1.316 | 0.838 | |||||||||||
Pull-out test results, CFRP sand coated #3 (9_52 mm diameter) bars
| Symbol | Bond strength | Loaded end slip | Free end slip | Bond stiffness | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| τb,max | Avg. | St.D. | C.O.V. | Slip a | Avg. | St.D. | C.O.V. | Slip a | Avg. | St.D. | C.O.V. | Avg. | ||
| (MPa) | (MPa) | (MPa) | (%) | (mm) | (mm) | (mm) | (%) | (mm) | (mm) | (mm) | (%) | (N/mm3) | ||
| C1 | 1 | 19.82 | 19.31 | 1.27 | 6.5 | 0.261 | 0.234 | 0.034 | 14.5 | 0.130 | 0.100 | 0.038 | 38.2 | 82.61 |
| 2 | 20.25 | 0.196 | 0.112 | |||||||||||
| 3 | 17.86 | 0.245 | 0.057 | |||||||||||
| C2 | 1 | 14.30 | 15.57 | 1.54 | 9.9 | 0.163 | 0.259 | 0.125 | 48.1 | 0.038 | 0.051 | 0.011 | 22.5 | 60.18 |
| 2 | 17.29 | 0.213 | 0.054 | |||||||||||
| 3 | 15.14 | 0.400 | 0.060 | |||||||||||
| C3 | 1 | 12.60 | 15.95 | 4.74 | 29.7 | 0.291 | 0.245 | 0.065 | 26.5 | 0.067 | 0.065 | 0.004 | 5.5 | 65.15 |
| 2 | 19.30 | 0.199 | 0.062 | |||||||||||
| S1 | 1 | 16.47 | 16.30 | 0.97 | 6.0 | 0.358 | 0.260 | 0.095 | 36.4 | 0.036 | 0.038 | 0.002 | 5.4 | 62.58 |
| 2 | 15.25 | 0.254 | 0.039 | |||||||||||
| 3 | 17.18 | 0.169 | 0.040 | |||||||||||
Pull-out test results, GFRP sand coated #3 (9_52 mm diameter) bars
| Symbol | Bond strength | Loaded end slip | Free end slip | Bond stiffness | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| τb,max | Avg. | St.D. | C.O.V. | Slip a | Avg. | St.D. | C.O.V. | Slip a | Avg. | St.D. | C.O.V. | Avg. | ||
| (MPa) | (MPa) | (MPa) | (%) | (mm) | (mm) | (mm) | (%) | (mm) | (mm) | (mm) | (%) | (N/mm3) | ||
| C1 | 1 | 12.87 | 14.11 | 4.26 | 30.2 | 0.397 | 0.406 | 0.156 | 38.3 | 0.038 | 0.075 | 0.052 | 69.5 | 34.76 |
| 2 | 18.85 | 0.566 | 0.134 | |||||||||||
| 3 | 10.60 | 0.255 | 0.052 | |||||||||||
| C2 | 1 | 9.54 | 9.16 | 0.74 | 8.1 | 0.255 | 0.256 | 0.069 | 27.0 | 0.040 | 0.026 | 0.012 | 48.0 | 35.74 |
| 2 | 8.30 | 0.188 | 0.022 | |||||||||||
| 3 | 9.63 | 0.326 | 0.016 | |||||||||||
| C3 | 1 | 8.21 | 13.03 | 6.82 | 52.3 | 0.238 | 0.374 | 0.192 | 51.4 | 0.034 | 0.054 | 0.028 | 52.4 | 34.87 |
| 2 | 17.86 | 0.509 | 0.074 | |||||||||||
| S1 | 1 | 9.24 | 10.97 | 2.44 | 22.3 | 0.297 | 0.297 | 0.001 | 0.2 | 0.044 | 0.057 | 0.018 | 32.3 | 36.98 |
| 2 | 12.70 | 0.296 | 0.070 | |||||||||||