Study on the Strength Characteristics and Microscopic Structure of Artificial Structural Loess
Abstract
1. Introduction
2. Materials and Methods
2.1. Test Materials
2.2. Sample Preparation
2.3. Test Method
2.3.1. Triaxial Shear Test
2.3.2. Microscopic Test
3. Results and Analysis
3.1. Analysis of Stress–Strain Curve
3.2. Analysis of Peak Strength Curve
3.3. Analysis of Shear Strength Index
3.4. Analysis of Mineral Composition in Loess
3.5. Analysis of Microstructure in Loess
3.6. Analysis of Pore Distribution in Loess
3.6.1. Pore Division of Structural Loess
3.6.2. Quantitative Analysis of Pore Distribution Characteristics
3.6.3. Analysis of Macro- and Microcorrelation
4. Conclusions
- The combined effect of the moisture content, pressure, and additive changes the stress–strain relationship of the artificial structural loess. Under the same pressure, when the cement dosage remains constant, the curve of the sample gradually moves downward with the increasing moisture content, and its breaking strength is negatively correlated with the moisture content. Under the same moisture content, the curve of the sample gradually increases with the increasing cement dosage, and its breaking strength shows a positive correlation with the cement dosage.
- The standard deviation of the peak strength for W16-Y2.0C2.0 is the smallest under various confining pressures, with 50 kPa being 6.481, 100 kPa being 7.676, and 200 kPa being 4.912. The minimum standard deviations of the cohesive inner friction angle are 2 kPa and 0.2°, respectively, corresponding to W16-Y2.0C2.0, indicating that the cohesive inner friction angle of W16-Y2.0C2.0 is the closest to that of the undisturbed sample. W16-Y2.0C2.0 is the optimal structural loess, and its structural strength is most similar to that of the undisturbed loess.
- The scatter patterns of the undisturbed loess and W16-Y2.0C2.0 are roughly similar. The characteristic peaks of cement and salt are not displayed in the diffraction pattern of W16-Y2.0C2.0. In addition, further quantitative analysis found that the differences in the mineral content between A and W16-Y2.0C2.0 are obtained. The stone salt is not detected in A, and the amphibole is not detected in W16-Y2.0C2.0.
- There exist many white cementing substances at the particle contact point of W16-Y2.0C2.0, which cause clay material to aggregate at the particle contact point, increasing the area and cohesion of the contact point. Some particles exhibit agglomeration, especially between small particles, which may be due to the increased electrostatic attraction or other forces between particles caused by the action of salt particles, resulting in particle aggregation, thus making the soil sample have similar structural strength and stability to those of the undisturbed soil.
- The pore distribution curve of the structural loess W16-Y2.0C2.0 has three peaks and is divided into four types of pores, including micropores (≤0.02 μm), small pores (0.02~0.21 μm), medium pores (0.21~13.5 μm), and large pores (≥13.5 μm). When the pressure increases from 50 kPa to 200 kPa, micropores increase by 4.67%, small pores increase by 4.97%, medium pores decrease by 2.4%, and large pores decrease by 7.24%. The trend of pore structure changes in W16-Y2.0C2.0 under pressure is similar to that of A.
- This study is based on laboratory standard conditions, without considering complex environmental factors such as wet–dry cycles, freeze–thaw effects, and dynamic loads that may exist in actual engineering. In the future, research will be conducted on the strength degradation mechanism of artificial structural loess under wet–dry cycles, freeze–thaw cycles, and chemical erosion. Although W16-Y2.0C2.0 exhibits strength characteristics similar to those of the undisturbed loess in the laboratory, considering the heterogeneity of the soil on site, fluctuations in moisture content, and dynamic changes in load, it is necessary to verify its universality.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Specific Gravity Gs | Natural Density ρ (g/cm3) | Natural Moisture Content w (%) | Dry Density ρd (g/cm3) | Maximum Dry Density ρd max (g/cm3) | Atterberg Limits (%) | Void Ratio e | Minimum Void Ratio emin | Maximum Void Ratio emax | Relative Density Dr (%) | |
---|---|---|---|---|---|---|---|---|---|---|
wp (%) | wL (%) | |||||||||
2.70 | 1.69 | 15.24 | 1.47 | 1.51 | 21.45 | 34.59 | 0.83 | 0.72 | 0.91 | 42.11 |
Test Method | Sample Type | Sample Name | Target Moisture Content w1 (%) | Salt Content (%) | Cement Content (%) | Confining Pressure (kPa) |
---|---|---|---|---|---|---|
CU | Undisturbed loess | A | 15.24 | / | / | 50, 100, 200 |
Artificial structural loess | W8-Y2.0C1.0 | 8 | 2 | 1 | ||
W8-Y2.0C2.0 | 2 | |||||
W8-Y2.0C4.0 | 4 | |||||
W16-Y2.0C1.0 | 16 | 1 | ||||
W16-Y2.0C2.0 | 2 | |||||
W16-Y2.0C4.0 | 4 | |||||
W24-Y2.0C1.0 | 24 | 1 | ||||
W24-Y2.0C2.0 | 2 | |||||
W24-Y2.0C4.0 | 4 |
Sample Type | Sample Name | Standard Deviation σf | ||
---|---|---|---|---|
50 kPa | 100 kPa | 200 kPa | ||
Undisturbed loess | A | 0 | 0 | 0 |
Artificial structural loess | W8-Y2.0C1.0 | 216.315 | 250.336 | 272.729 |
W8-Y2.0C2.0 | 264.439 | 300.243 | 362.943 | |
W8-Y2.0C4.0 | 329.803 | 366.657 | 523.901 | |
W16-Y2.0C1.0 | 61.848 | 34.155 | 39.646 | |
W16-Y2.0C2.0 | 6.481 | 7.676 | 4.912 | |
W16-Y2.0C4.0 | 60.384 | 54.208 | 50.369 | |
W24-Y2.0C1.0 | 248.556 | 242.621 | 309.983 | |
W24-Y2.0C2.0 | 232.994 | 225.367 | 285.138 | |
W24-Y2.0C4.0 | 207.362 | 189.434 | 233.853 |
Sample Type | Sample Name | Standard Deviation σf | |
---|---|---|---|
c (kPa) | φ (°) | ||
Undisturbed loess | A | 0 | 0 |
Artificial structural loess | W8-Y2.0C1.0 | 44.8 | 1.8 |
W8-Y2.0C2.0 | 16.7 | 0.8 | |
W8-Y2.0C4.0 | 54.2 | 3 | |
W16-Y2.0C1.0 | 29.8 | 4.4 | |
W16-Y2.0C2.0 | 2 | 0.2 | |
W16-Y2.0C4.0 | 51.3 | 2.5 | |
W24-Y2.0C1.0 | 24.2 | 6.4 | |
W24-Y2.0C2.0 | 17.3 | 0.4 | |
W24-Y2.0C4.0 | 46.5 | 1.3 |
Sample Name | Pressure (kPa) | Standard Deviation σf | |||
---|---|---|---|---|---|
Micropores | Small Pores | Medium Pores | Medium Pores | ||
W16-Y2.0C2.0 | 50 | 0.17 | 10.07 | 4.75 | 5.15 |
200 | 4.1 | 3.81 | 2.64 | 5.27 |
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Zhang, Y.; Qin, J.; Li, G.; Shao, M.; Gao, S. Study on the Strength Characteristics and Microscopic Structure of Artificial Structural Loess. Buildings 2025, 15, 1761. https://doi.org/10.3390/buildings15111761
Zhang Y, Qin J, Li G, Shao M, Gao S. Study on the Strength Characteristics and Microscopic Structure of Artificial Structural Loess. Buildings. 2025; 15(11):1761. https://doi.org/10.3390/buildings15111761
Chicago/Turabian StyleZhang, Yao, Jianxiang Qin, Gang Li, Minghang Shao, and Shuaifeng Gao. 2025. "Study on the Strength Characteristics and Microscopic Structure of Artificial Structural Loess" Buildings 15, no. 11: 1761. https://doi.org/10.3390/buildings15111761
APA StyleZhang, Y., Qin, J., Li, G., Shao, M., & Gao, S. (2025). Study on the Strength Characteristics and Microscopic Structure of Artificial Structural Loess. Buildings, 15(11), 1761. https://doi.org/10.3390/buildings15111761