The Feasibility of Modified Magnesia-Phosphate Cement as a Heat Resistant Adhesive for Strengthening Concrete with Carbon Sheets
Abstract
:1. Introduction
2. Experimental
2.1. Raw Materials
2.2. Testing Methods
2.2.1. Bond Strength
2.2.2. Preparation of Specimens
2.2.3. Elevated Temperature Treatment
2.2.4. Microscopic Characterization
3. Results and Discussion
3.1. Failure Modes
3.2. Bond Properties at Room Temperature
3.3. Failure Modes after Exposure to High Temperatures
3.3.1. Experimental Phenomena
3.3.2. Failure Modes
3.4. Bond Strength after Exposure to High Temperatures
3.4.1. Influence of Wollastonite Addition
3.4.2. Comparison between Modified MPC and Epoxy
4. Conclusions
- In the double-shear test, six key failure modes occurred for concrete specimens at ambient and elevated temperatures. The delamination of carbon fiber sheet is the dominant one for the MPC specimens under temperatures below 200 °C. The MPC specimens failed in the adhesive layer at higher temperatures. The complete debonding failure between the adhesive and the concrete substrate happened for the epoxy resin specimens under temperatures lower than 200 °C. Peeling off of the carbon fiber sheet happened for the epoxy resin specimens after exposure to 300 °C.
- With the increasing compressive strength of concrete specimen, the higher bond strength between carbon fiber sheets and concrete specimen was measured. The bond strength for the MPC specimens is slightly higher than that for the epoxy resin specimen at ambient temperature, and the former reveals a much higher residual bond strength than the latter after exposure to temperatures from 105 °C to 500 °C.
- Although the MPC specimens failed through interlaminar slip of fiber strips instead of complete debonding, the improved bond strength under ambient temperature and higher temperatures revealed that the modified magnesia-phosphate cement could be a good substitute for epoxy resin in repairing and/or strengthening structural elements. Furthermore, the use of the modified MPC as the binder between the carbon fiber sheets and concrete can be less expensive and an ecologically friendly alternative.
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Mix | Wollastonite (Molar Percent) | MgO (Molar Percent) | Weight Dosage | ||
---|---|---|---|---|---|
Wollastonite | MgO | ADP | |||
MA1 (control) | 0 | 100 | 0 | 100 | 31.9 |
MA2 (5%) | 5 | 95 | 15.3 | 100 | 33.6 |
MA3 (10%) | 10 | 90 | 32.2 | 100 | 35.5 |
Property | Carbon Fiber Sheets | Epoxy Resin |
---|---|---|
Elastic Modulus (GPa) | 244 | 19 |
Tensile strength (MPa) | 4125 | 39.12 |
Areal Density (g/m2) | 300 | - |
Nominal Thickness (mm) | 0.167 | - |
Compressive Strength of Concrete fcu.m (MPa) | Curing Age (Days) | Bond Strength(MPa) |
---|---|---|
30.95 | 3 | 1.50 |
7 | 1.71 | |
28 | 1.82 | |
42.67 | 3 | 1.61 |
7 | 1.75 | |
28 | 1.88 | |
49.89 | 3 | 1.68 |
7 | 1.87 | |
28 | 2.01 |
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Zhang, A.; Gao, X. The Feasibility of Modified Magnesia-Phosphate Cement as a Heat Resistant Adhesive for Strengthening Concrete with Carbon Sheets. Appl. Sci. 2016, 6, 178. https://doi.org/10.3390/app6060178
Zhang A, Gao X. The Feasibility of Modified Magnesia-Phosphate Cement as a Heat Resistant Adhesive for Strengthening Concrete with Carbon Sheets. Applied Sciences. 2016; 6(6):178. https://doi.org/10.3390/app6060178
Chicago/Turabian StyleZhang, Ailian, and Xiaojian Gao. 2016. "The Feasibility of Modified Magnesia-Phosphate Cement as a Heat Resistant Adhesive for Strengthening Concrete with Carbon Sheets" Applied Sciences 6, no. 6: 178. https://doi.org/10.3390/app6060178