Geotechnical Behaviour of Fly Ash–Bentonite Used in Layers
Abstract
:1. Introduction
2. Materials Used
2.1. Fly Ash
2.2. Bentonite
3. Experimental Programme
3.1. Sample Preparation
3.2. Test Procedure
4. Results and Discussion
4.1. Stress-Strain Behaviour
4.2. Shear Strength Parameters
5. Conclusions
- Fly ash is a nearly cohesionless substance that has a binding effect at the fly ash–bentonite layered system interfaces.
- For F:B = 1:1, 1:2, 1:3, and 1:4, the value of cohesion has been varied in the ranges of 76.8–107 kPa, 75–110 kPa, 66.6–105 kPa, and 55–78.2 kPa, respectively, for different layer arrangements. As the ratio of fly ash to bentonite is increased, the value of cohesion is decreased, while at the same ratio, the value of cohesion is increased by increasing the number of interfaces.
- For F:B = 1:1, 1:2, 1:3, and 1:4, the value of angle of shearing resistance has been varied in the range of 17–22.8° for different layer arrangements. The value of the angle of shearing resistance has been found to decreases with the increase in the number of interfaces for a specified ratio of fly ash to bentonite.
- The stress–strain behaviour of the fly ash–bentonite layered system is initially elastic at low stress levels and becomes non-linear at higher stress levels.
- As the number of interfaces and confining pressures grow, the shear strength and net safe bearing capacity of the fly ash–bentonite layered system increases.
- Based on laboratory model tests, it has been suggested that the embankment may provide greater stability if it is constructed for a fly ash to bentonite ratio of 3:1 (75% of fly ash and 25% of bentonite in layers) by keeping the number of interfaces as N = 3.
- It has been found that a 3:1 ratio of fly ash to bentonite with three interfaces can be successfully used for filling low-lying areas and in many other engineering constructions, while also providing a means of using the material without negatively impacting the environment. However, the authors recommend that large-scale studies be conducted in the future.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Composition | Percentage |
---|---|
Silicon dioxide (SiO2) | 59.00 |
Alumina (Al2O3) | 29.00 |
Iron oxide (Fe2O3) | 6.50 |
Calcium oxide (CaO) | 1.80 |
Magnesium oxide (MgO) | 1.44 |
Sodium oxide (Na2O) | 0.80 |
Sulphur trioxide (SO3) | 0.28 |
Properties | Fly Ash | Bentonite |
---|---|---|
Specific gravity | 2.19 | 2.73 |
Optimum moisture content (OMC), % | 22 | 28 |
Unit weight, kN/m3 | 14.39 | 21.5 |
Maximum dry density (MDD), kN/m3 | 11.8 | 16.8 |
Liquid limit (WL), % | 24 | 261 |
Plastic limit (WP), % | Non plastic | 38 |
Plasticity index (P.I), % | 24 | 223 |
Coefficient of permeability, (10−10 m/sec) | 551 | 8.52 |
Unconfined compression strength, kN/m2 | 34 | 176 |
Classification | Class F | CH |
Test Description | No. of Interfaces (N) | Confining Pressure (kPa) | Total No. of Tests | ||
---|---|---|---|---|---|
100 | 200 | 300 | |||
Fly Ash Sample | - | ✓ | ✓ | ✓ | 6 |
Bentonite Sample | - | ✓ | ✓ | ✓ | 6 |
F:B = 1:1 | 1 | ✓ | ✓ | ✓ | 6 |
2 | ✓ | ✓ | ✓ | 6 | |
3 | ✓ | ✓ | ✓ | 6 | |
F:B = 2:1 | 1 | ✓ | ✓ | ✓ | 6 |
2 | ✓ | ✓ | ✓ | 6 | |
3 | ✓ | ✓ | ✓ | 6 | |
F:B = 3:1 | 1 | ✓ | ✓ | ✓ | 6 |
2 | ✓ | ✓ | ✓ | 6 | |
3 | ✓ | ✓ | ✓ | 6 | |
F:B = 4:1 | 1 | ✓ | ✓ | ✓ | 6 |
2 | ✓ | ✓ | ✓ | 6 | |
3 | ✓ | ✓ | ✓ | 6 |
F:B | Cohesion (c), kPa | Angle of Internal Friction (ϕ), ° | ||||
---|---|---|---|---|---|---|
N = 1 | N = 2 | N = 3 | N = 1 | N = 2 | N = 3 | |
1:1 | 76.8 | 83.4 | 107 | 22.5 | 22.2 | 20 |
2:1 | 75 | 76.1 | 110 | 21 | 20 | 17 |
3:1 | 66.6 | 86 | 105 | 21.5 | 20 | 21.5 |
4:1 | 55 | 59 | 78.2 | 22.8 | 22.8 | 22 |
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Hasan, M.; Khan, M.A.; Alsabhan, A.H.; Almajid, A.A.; Alam, S.; Khan, M.A.; Biswas, T.; Pu, J. Geotechnical Behaviour of Fly Ash–Bentonite Used in Layers. Appl. Sci. 2022, 12, 1421. https://doi.org/10.3390/app12031421
Hasan M, Khan MA, Alsabhan AH, Almajid AA, Alam S, Khan MA, Biswas T, Pu J. Geotechnical Behaviour of Fly Ash–Bentonite Used in Layers. Applied Sciences. 2022; 12(3):1421. https://doi.org/10.3390/app12031421
Chicago/Turabian StyleHasan, Murtaza, Mehboob Anwer Khan, Abdullah H. Alsabhan, Abdullah A. Almajid, Shamshad Alam, Mohammad Amir Khan, Tinku Biswas, and Jaan Pu. 2022. "Geotechnical Behaviour of Fly Ash–Bentonite Used in Layers" Applied Sciences 12, no. 3: 1421. https://doi.org/10.3390/app12031421
APA StyleHasan, M., Khan, M. A., Alsabhan, A. H., Almajid, A. A., Alam, S., Khan, M. A., Biswas, T., & Pu, J. (2022). Geotechnical Behaviour of Fly Ash–Bentonite Used in Layers. Applied Sciences, 12(3), 1421. https://doi.org/10.3390/app12031421