Research on the Effect of Desert Sand on Pore Structure of Fiber Reinforced Mortar Based on X-CT Technology
Abstract
:1. Introduction
2. Materials and Methods
2.1. Raw Materials
2.2. Test Methods
2.2.1. Compressive Strength
2.2.2. Mercury Intrusion Porosimetry (MIP)
2.2.3. μX-CT
Porosity Calculation Based on Two-Dimensional CT Images
Modeling and Analysis of Pore Structure Based on Avizo Software
3. Results and Discussion
3.1. Compressive Strength
3.2. Analysis of MIP
3.3. Analysis of μX-CT
3.3.1. Pore Characteristic Analysis Based on Two-Dimensional CT Images
3.3.2. Pore Structure Analysis Based on 3D Modeling
3.4. Discussion
4. Conclusions
- This paper studied the effect of desert sand on fiber reinforced mortar. The compressive strength increases first and then decreases at different rates with the increase of desert sand replacement rate. After curing for 28 days, relative to river sand mortar, the increment of compressive strength of fiber reinforced mortar with 25%, 50%, 75%, and 100% desert sand replacement rate is 8.61%, 11.90%, 8.96%, and 2.28%, respectively. Mortar with 50% desert sand replacement rate has the highest compressive strength, up to 98.7 MPa, which has a positive effect on the application of desert sand in concrete.
- MIP and μX-CT techniques were used to study the pore structure of fiber reinforced mortar with different desert sand replacement rate. The changes of pore structure characteristics obtained by MIP and μX-CT are basically consistent. The MIP technique was used to study the pore structure characteristics from 1 nm to 500 μm, and the pore size changes are mainly distributed in the range of 1–100 nm and over 200 μm. It is found that when the replacement rate of desert sand exceeds 50%, the pore structure characteristics measured by MIP in the range of 1 nm to 100 nm are worse than those of the reference group, indicating that the pore structure characteristics are inferior to those of pure river sand fiber reinforced mortar. The μX-CT technique was used to investigate the pore structure characteristics above 200 μm. The pores in this range are more harmful pores and have a great influence on the strength of cement mortar. When the replacement rate of desert sand exceeds 50%, the pore structure becomes worse in the range of 200 μm, but it is still better than pure river sand group. This indicates that the pore over than 200 μm has a greater influence on the strength of fiber reinforced mortar.
- Two methods were used to analyze the pore structure of samples based on μX-CT technique. The first method calculates the porosity of each CT image to obtain the porosity at different depths and total porosity. The second method models the pore structure based on Avizo software to obtain a three-dimensional model of the pore structure. The changes of pore structure characteristics obtained by the two methods are basically the same, and the porosity values remain the same. In comparison, it is an efficient and convenient method to analyze the pore structure of concrete by 3D modeling. It cannot only make the pore structure of samples become visualized and more intuitively observe the changes of the pore structure, but also quantitatively analyze the pore structure of samples through the data analysis method in the Avizo software.
- The compressive strength of fiber reinforced mortar with different desert sand re-placement rate decreases with the increase of porosity. When the desert sand replacement rate is 50%, the sample has the lowest porosity, the best pore structure characteristics, and the highest compressive strength. The optimization of pore structure can effectively improve the microstructure of cement mortar, make the microstructure of cement mortar become more compact, and improve the compressive strength.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Items | Chemical Composition/% | Ignition Loss Rate | Specific Surface Area/(cm2/g) | Packing Density/(g/cm3) | ||||||
---|---|---|---|---|---|---|---|---|---|---|
CaO | SiO2 | Al2O3 | MgO | Fe2O3 | Na2O | SO3 | ||||
Cement | 61.54 | 15.40 | 4.43 | 0.72 | 4.91 | 0.04 | 2.75 | 2.24 | 3500 | 3.1 |
Group | Cement | Steel Fiber | Desert Sand Replacement Rate% | Desert Sand | River Sand | Deionized Water |
---|---|---|---|---|---|---|
1 | 1 | 0.30 | 0 | \ | 1.2 | 0.45 |
2 | 1 | 0.30 | 25 | 0.3 | 0.9 | 0.45 |
3 | 1 | 0.30 | 50 | 0.6 | 0.6 | 0.45 |
4 | 1 | 0.30 | 75 | 0.9 | 0.3 | 0.45 |
5 | 1 | 0.30 | 100 | 1.2 | \ | 0.45 |
Group | 1 | 2 | 3 | 4 | 5 |
---|---|---|---|---|---|
Porosity (%) | 14.0821 | 13.0013 | 12.7888 | 15.1259 | 16.5675 |
Cumulative pore volume (mL/g) | 0.0729 | 0.0672 | 0.0662 | 0.0815 | 0.0928 |
Mean diameter (nm) | 40,625 | 40,606 | 40,598 | 40,618 | 40,630 |
Start from the Top Surface | Porosity/% | Start from the Top Surface | Porosity/% | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | ||
0–1 mm | 3.41 | 3.04 | 2.72 | 2.85 | 3.15 | 25–26 mm | 2.78 | 2.65 | 1.60 | 1.92 | 2.51 |
1–2 mm | 3.34 | 3.37 | 2.53 | 2.70 | 3.12 | 26–27 mm | 2.49 | 1.98 | 1.95 | 2.10 | 2.68 |
2–3 mm | 3.58 | 3.34 | 2.69 | 2.74 | 3.45 | 27–28 mm | 2.80 | 1.65 | 2.25 | 2.45 | 2.82 |
3–4 mm | 3.62 | 3.17 | 2.70 | 3.19 | 3.41 | 28–29 mm | 2.75 | 2.56 | 2.22 | 2.41 | 2.65 |
4–5 mm | 3.88 | 3.26 | 2.61 | 3.21 | 3.29 | 29–30 mm | 2.56 | 2.48 | 2.26 | 1.69 | 2.50 |
5–6 mm | 3.56 | 3.11 | 2.70 | 3.20 | 3.13 | 30–31 mm | 2.78 | 2.40 | 2.03 | 1.71 | 2.81 |
6–7 mm | 3.45 | 2.97 | 2.66 | 3.33 | 3.27 | 31–32 mm | 2.30 | 1.95 | 1.69 | 1.51 | 2.77 |
7–8 mm | 3.41 | 2.99 | 2.91 | 2.89 | 2.91 | 32–33 mm | 2.56 | 1.85 | 1.96 | 1.43 | 2.95 |
8–9 mm | 3.51 | 2.96 | 2.69 | 3.04 | 3.79 | 33–34 mm | 2.48 | 1.86 | 1.06 | 1.79 | 2.80 |
9–10 mm | 3.55 | 2.84 | 3.21 | 2.74 | 3.96 | 34–35 mm | 2.95 | 1.56 | 1.05 | 1.46 | 2.58 |
10–11 mm | 3.50 | 2.74 | 2.63 | 2.83 | 4.00 | 35–36 mm | 2.54 | 1.59 | 1.28 | 1.20 | 2.70 |
11–12 mm | 3.56 | 2.79 | 2.65 | 2.98 | 3.74 | 36–37 mm | 2.39 | 1.48 | 1.19 | 1.57 | 2.06 |
12–13 mm | 3.34 | 2.99 | 2.74 | 2.90 | 3.27 | 37–38 mm | 2.30 | 1.33 | 1.26 | 1.57 | 2.05 |
13–14 mm | 3.59 | 3.12 | 2.50 | 2.96 | 2.97 | 38–39 mm | 2.56 | 1.43 | 1.15 | 1.07 | 2.58 |
14–15 mm | 3.45 | 3.05 | 2.65 | 3.02 | 2.90 | 39–40 mm | 1.96 | 1.08 | 1.12 | 1.39 | 2.70 |
15–16 mm | 3.56 | 2.65 | 2.25 | 1.92 | 2.53 | 40–41 mm | 1.89 | 1.12 | 1.29 | 1.62 | 2.06 |
16–17 mm | 3.55 | 2.75 | 2.36 | 1.71 | 2.49 | 41–42 mm | 1.41 | 1.26 | 1.35 | 1.88 | 1.89 |
17–18 mm | 3.23 | 2.99 | 2.71 | 2.57 | 2.42 | 42–43 mm | 1.30 | 1.26 | 1.04 | 2.29 | 1.64 |
18–19 mm | 3.26 | 3.01 | 1.60 | 2.58 | 3.14 | 43–44 mm | 1.21 | 1.94 | 1.05 | 1.43 | 1.41 |
19–20 mm | 3.10 | 2.91 | 1.51 | 1.79 | 3.05 | 44–45 mm | 1.32 | 1.55 | 1.03 | 1.27 | 1.36 |
20–21 mm | 2.77 | 2.90 | 1.79 | 1.60 | 2.99 | 45–46 mm | 1.20 | 1.06 | 1.11 | 1.14 | 1.40 |
21–22 mm | 2.78 | 2.81 | 1.65 | 1.92 | 2.60 | 46–47 mm | 1.04 | 1.05 | 1.03 | 1.01 | 1.25 |
22–23 mm | 2.51 | 2.86 | 1.95 | 2.33 | 2.53 | 47–48 mm | 1.02 | 1.00 | 0.97 | 1.05 | 1.21 |
23–24 mm | 2.65 | 2.65 | 2.26 | 1.79 | 2.42 | 48–49 mm | 0.89 | 0.85 | 0.74 | 0.74 | 0.96 |
24–25 mm | 2.61 | 2.61 | 1.89 | 1.60 | 2.73 | 49–50 mm | 0.74 | 0.73 | 0.69 | 0.73 | 0.75 |
The upper area | 3.51 | 3.02 | 2.68 | 2.91 | 3.30 | \ | \ | \ | \ | \ | \ |
The middle area | 2.80 | 2.57 | 1.98 | 1.99 | 2.69 | \ | \ | \ | \ | \ | \ |
The bottom area | 1.76 | 1.33 | 1.13 | 1.37 | 1.91 | \ | \ | \ | \ | \ | \ |
Average | 2.70 | 2.27 | 1.89 | 2.09 | 2.64 | \ | \ | \ | \ | \ | \ |
Group | 1 | 2 | 3 | 4 | 5 |
---|---|---|---|---|---|
Porosity | 2.02% | 1.92% | 1.84% | 1.89% | 1.85% |
Pore size Distribution(μm) | 254.273–4959.207 | 176.27–4883.869 | 233.89–3485.766 | 176.27–3695.517 | 176.27–8232.703 |
Mean Pore Volume(mm3) | 0.2094 | 0.1960 | 0.1906 | 0.2009 | 0.2052 |
Min Pore Volume(mm3) | 0.0412 | 0.0412 | 0.0412 | 0.0399 | 0.0401 |
Max Pore Volume(mm3) | 87.8677 | 66.4778 | 25.9235 | 15.6972 | 90.8732 |
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Shi, F.; Li, T.; Wang, W.; Liu, R.; Liu, X.; Tian, H.; Liu, N. Research on the Effect of Desert Sand on Pore Structure of Fiber Reinforced Mortar Based on X-CT Technology. Materials 2021, 14, 5572. https://doi.org/10.3390/ma14195572
Shi F, Li T, Wang W, Liu R, Liu X, Tian H, Liu N. Research on the Effect of Desert Sand on Pore Structure of Fiber Reinforced Mortar Based on X-CT Technology. Materials. 2021; 14(19):5572. https://doi.org/10.3390/ma14195572
Chicago/Turabian StyleShi, Fangying, Tianyu Li, Weikang Wang, Ruidan Liu, Xiaoyan Liu, Huiwen Tian, and Nazhen Liu. 2021. "Research on the Effect of Desert Sand on Pore Structure of Fiber Reinforced Mortar Based on X-CT Technology" Materials 14, no. 19: 5572. https://doi.org/10.3390/ma14195572