Effects of Multi-Walled Carbon Nanotubes on Mechanical Properties and Microstructure of Ordinary Portland Cement–Sulfoaluminate Cement Repair Mortar
Abstract
1. Introduction
2. Experimental Schemes
2.1. Materials
2.2. Sample Preparation
2.3. Dispersion of MWCNTs
2.4. Test Programs
3. Results and Discussion
3.1. Mechanical Properties
3.2. X-Ray Diffraction
3.3. TG Analysis
3.4. X-CT Analysis
3.5. MIP Analysis
3.6. SEM Analysis
4. Conclusions
- Incorporation of MWCNTs improves the mechanical strength of OPC-SAC mortar. Contrary to that of OPC-SAC mortar without MWCNTs, the compressive strength of OPC-SAC mortar with 0.10 wt.% MWCNTs increased by 10.39%/9.3 MPa at most. Meanwhile, the flexural strength can be increased by 15.70%/1.9 MPa by adding 0.075 wt.% MWCNTs.
- Dispersed MWCNTs promote hydration of OPC-SAC composites (especially in the early stages) through functional group and nucleation effects, but did not promote the formation of new substances.
- The X-CT, MIP, and SEM results indicate that the MWCNTs optimizes the microstructure and microstructure of the composites. One role is to cause partial cross-linking occurs between hydration products, which enhances the complexity (higher Ds) and integrity of the binder (more cross-linking sites). The other one is to reduce the generation and propagation of microcracks through nanofiber bridging. The third is to optimize the pore structure and reduce the porosity, especially the volume of medium capillary pores.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Mass Fraction (w/%) | CaO | Al2O3 | SiO2 | Fe2O3 | MgO | SO3 | K2O | Na2O | LOI |
---|---|---|---|---|---|---|---|---|---|
OPC | 68.62 | 3.42 | 17.52 | 4.61 | 1.79 | 1.23 | 1.10 | 0.66 | 1.05 |
SAC | 42.70 | 36.27 | 6.56 | 2.48 | 1.55 | 8.75 | 0.17 | 0.22 | 0.70 |
Out Diameter (nm) | Inner Diameter (nm) | Length (um) | Specific Surface Area (m2/g) | Purity (%) |
---|---|---|---|---|
10–20 | 5–10 | 20–30 | ˃250 | ˃95 |
Sample Code | MWCNTs | OPC | SAC | Sand | Water | Superplasticizer |
---|---|---|---|---|---|---|
MT-0 | 0 | 800.0 | 200.0 | 800 | 250 | 6 |
MT-0.05 | 0.50 | 799.6 | 199.9 | 800 | 250 | 8 |
MT-0.075 | 0.75 | 799.4 | 199.9 | 800 | 250 | 8 |
MT-0.10 | 1.00 | 799.2 | 199.8 | 800 | 250 | 10 |
MT-0.125 | 1.25 | 799.0 | 199.8 | 800 | 250 | 10 |
MT-0.15 | 1.50 | 798.8 | 199.7 | 800 | 250 | 12 |
Simple Code | Porosity (%) | Equivalent Diameter (μm) | Pore Quantity |
---|---|---|---|
MT-0 | 0.82 | 86.1 | 27,042 |
MT-0.10 | 0.45 | 70.3 | 22,874 |
Sample Code | Most Probable Aperture/nm | Average Pore Diameter/nm | Medium Pore Diameter/nm | Porosity/% |
---|---|---|---|---|
MT-0 | 40.3 | 22.5 | 55.6 | 15.17 |
MT-0.10 | 40.3 | 17.8 | 43.4 | 13.34 |
MT-0.15 | 45.3 | 19.0 | 43.9 | 15.86 |
Simple Code | Mesopores | Macropores | ||
---|---|---|---|---|
Fractal Dimension | Correlation | Fractal Dimension | Correlation | |
MT-0 | 2.365 | 0.990 | 2.760 | 0.997 |
MT-0.10 | 2.341 | 0.989 | 2.720 | 0.997 |
MT-0.15 | 2.371 | 0.988 | 2.756 | 0.997 |
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Zhou, Q.; Cao, R.; Ma, X. Effects of Multi-Walled Carbon Nanotubes on Mechanical Properties and Microstructure of Ordinary Portland Cement–Sulfoaluminate Cement Repair Mortar. Materials 2025, 18, 3748. https://doi.org/10.3390/ma18163748
Zhou Q, Cao R, Ma X. Effects of Multi-Walled Carbon Nanotubes on Mechanical Properties and Microstructure of Ordinary Portland Cement–Sulfoaluminate Cement Repair Mortar. Materials. 2025; 18(16):3748. https://doi.org/10.3390/ma18163748
Chicago/Turabian StyleZhou, Qun, Runzhuo Cao, and Xiaodong Ma. 2025. "Effects of Multi-Walled Carbon Nanotubes on Mechanical Properties and Microstructure of Ordinary Portland Cement–Sulfoaluminate Cement Repair Mortar" Materials 18, no. 16: 3748. https://doi.org/10.3390/ma18163748
APA StyleZhou, Q., Cao, R., & Ma, X. (2025). Effects of Multi-Walled Carbon Nanotubes on Mechanical Properties and Microstructure of Ordinary Portland Cement–Sulfoaluminate Cement Repair Mortar. Materials, 18(16), 3748. https://doi.org/10.3390/ma18163748