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Fig. 3.
Fig. 4.
Fig. 5.
Fig. 6.
Fig. 7.
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Fig. 9.
Fig. 10.
Fig. 11.
Summary of EIS measurements for N80 steel
| Sample | Rel+b (kΩ/cm2) | Qpn, | n | Rpn (kΩ/cm2) | Qpn, | n | Rct (kΩ/cm2) |
|---|---|---|---|---|---|---|---|
| Before CO2 exposure | 84.03±3.20 | 5.78E−09±2.89E−10 | 0.5708±0.0285 | 30.24±1.21 | 1.05E−04±5.25E−06 | 0.6877±0.0344 | 355.21±14.21 |
| After CO2 exposure | 22.24±0.89 | 2.53E−09±1.26E−10 | 0.5541±0.0277 | 2.99±0.12 | 1.73E−03±8.65E−05 | 0.8153±0.0408 | 200.40±8.02 |
Ultrasonic Testing results for the steel-cement interface
| Exposure Duration (Months) | Acoustic Impedance (MRayl) | Velocity of Sound (m/s) | Signal Amplitude (dB) |
|---|---|---|---|
| 0 (Control) | 45.0±4.3 | 5940±80 | −12.5±0.5 |
| 1 | 43.5±3.2 | 5720±70 | −10.4±0.3 |
| 2 | 42.7±1.5 | 5610±60 | −9.7±0.4 |
| 3 | 40.0±3.2 | 5570±60 | −8.5±0.5 |
| 4 | 38.5±2.4 | 5550±70 | −7.2±0.4 |
| 5 | 36.2±2.0 | 5430±80 | −6.5±0.3 |
| 6 | 34.1±1.4 | 5370±50 | −5.9±0.4 |
ICP-MS results showing ion flux in CO2 environments
| Exposure Duration (Months) | Iron Concentration (ppm) in Brine | Calcium Concentration (ppm) in Brine | Silicon Concentration (ppm) in Brine |
|---|---|---|---|
| 0 (Control) | 0.5±0.08 | 1.2±0.12 | 0.8±0.05 |
| 1 | 1.1±0.07 | 1.8±0.09 | 1.2±0.08 |
| 2 | 2.0±0.09 | 2.5±0.30 | 1.7±0.05 |
| 3 | 3.2±0.12 | 3.5±0.25 | 2.3±0.06 |
| 4 | 4.5±0.22 | 4.8±0.33 | 3.1±0.07 |
| 5 | 5.9±0.21 | 6.2±0.51 | 4.0±0.12 |
| 6 | 7.5±0.43 | 7.9±0.34 | 5.2±0.44 |
Nano-indentation test results for cement paste
| Exposure Duration (Months) | Hardness (GPa) | Elastic Modulus (GPa) | Indentation Depth (μ m) |
|---|---|---|---|
| 0 (Control) | 1.25±0.04 | 25.0±0.36 | 2.50±0.04 |
| 1 | 1.15±0.03 | 23.8±0.65 | 2.65±0.07 |
| 2 | 1.05±0.07 | 22.6±0.44 | 2.80±0.03 |
| 3 | 0.95±0.03 | 21.4±0.27 | 2.95±0.08 |
| 4 | 0.85±0.04 | 20.2±1.03 | 3.15±0.11 |
| 5 | 0.75±0.05 | 19.0±0.85 | 3.30±0.09 |
| 6 | 0.65±0.06 | 17.8±0.78 | 3.50±0.14 |
Electrochemical parameters of steel at the interface
| Exposure Duration (Months) | Corrosion Potential (mV, SCE) | Corrosion Current Density (μA/cm2) | Polarization Résistance (kΩ/cm2) |
|---|---|---|---|
| 0 (Control) | −453±13 | 0.5±0.03 | 20±0.4 |
| 1 | −472±11 | 0.8±0.04 | 18±0.6 |
| 2 | −497±10 | 1.2±0.03 | 16±0.7 |
| 3 | −514±7 | 1.6±0.04 | 13±0.5 |
| 4 | −532±11 | 2.1±0.03 | 10±0.9 |
| 5 | −553±14 | 2.7±0.02 | 8±0.7 |
| 6 | −572±7 | 3.4±0.03 | 5±0.8 |