Study on the Reuse of Shield Mud from Clay Stratum in Synchronous Grouting Slurry
Abstract
:1. Introduction
2. Materials and Methods
2.1. Materials
2.2. Test Scheme
2.3. Performance Requirements for Synchronized Grouting Materials
2.4. Test Method
3. Analysis of Test Results
3.1. The Influence Factors of Shield Mud Content on Slurry Performance
3.1.1. Effect of Shield Mud Content on Slurry Fluidity
3.1.2. Effect of Shield Mud Content on Slurry Stability
3.1.3. Effect of Shield Mud Content on Slurry Strength
3.2. Improvement Scheme of Initial Value of Slurry Consistency
3.2.1. Liquidity Improvement Effect
3.2.2. Strength Improvement Effect
3.3. Improvement Scheme of Slurry Fluidity Gradual Loss
3.3.1. Effect of Water-Reducing Agent on Slurry Fluidity
3.3.2. Effect of Water Reducer on Slurry Stability
3.3.3. Effect of Water Reducer on Slurry Strength
3.4. Study on Water Dispersion Resistance of Slurry
3.4.1. The Influence of HEMC on pH Value and Turbidity Value of Slurry
3.4.2. The Influence of HEMC Content on Slurry Fluidity
3.4.3. Effect of HEMC on the Water-to-Ground Strength Ratio of Slurries
4. Microscopic Test Results and Analysis
4.1. X-ray Diffraction
4.2. Scanning Electron Microscopy
5. Conclusions
- (1)
- Tests showed that, when using clay strata shield mud to replace the fly ash in synchronous grouting material, with replacement percentages of 20%~100%, the slurry achieved good compressive strength and stability, but at the same time led to slurry consistency and slump diameter of the initial value, and the time loss was too large. At a shield mud replacement of 80%, the slurry had a stronger compressive strength and a shorter coagulation time, so the use of shield mud can not only reduce project expenditure, but also greatly shorten the project duration.
- (2)
- An experiment was conducted to investigate the effects of different water–binder ratios on the consistency, slump, and compressive strength of shield mud simultaneous grouting slurries. The results indicate that adjusting the water–binder ratio significantly improved the initial consistency of the slurry. When the water–binder ratio was 0.445, the initial consistency and slump of the slurry met the specification requirements. Furthermore, it exhibited optimal compressive strength.
- (3)
- By increasing the dosage of the polycarboxylate superplasticizer agent, the fluidity and stability of the synchronized grouting slurry could be effectively improved, and its strength showed a steady growth trend. When the dosage of the polycarboxylate superplasticizer agent was 0.24%, the slurry showed optimal performance, especially regarding the flow time loss, which significantly improved. However, if the dosage of the polycarboxylate superplasticizer agent is too high, it will lead to excessive fluidity performance of the slurry, and, at the same time, there will be no phenomenon of segregation of the slurry.
- (4)
- In this study, it was found that, as the content of hydroxyethyl methyl cellulose (HEMC) in the slurry increased, the turbidity and pH of the slurry decreased and the consistency slightly reduced, while the setting time of the mortar was significantly delayed. The water dispersion resistance of the mortar was improved with 0.04% HEMC. At the same time, when the HEMC content is too high, it will seriously affect the compressive strength and fluidity of the slurry, so in the tunnel construction process, the actual water content of the geological survey environment should be used to determine the dosage of HEMC, as an excessive HEMC dosage will have a negative impact on the slurry.
- (5)
- After replacing fly ash with shield tunneling mud, XRD analysis showed a decrease in CaCO3 diffraction peaks in the shield tunneling mud, while the C-S-H diffraction peaks in the grout solution simultaneously increased, enhancing the strength formation capability. SEM analysis revealed that, in the replaced samples (A4, T3, and T4), there was a reduction in fly ash particles and the appearance of numerous interlaced hydration products, ensuring strength enhancement in the grout’s later stages. Meanwhile, the air-entraining effect of HEMC caused the loosening of the internal structure in sample T4. An analysis of the 1 μm level showed that the addition of a polyhydroxy acid water reducer delayed the hydration time and promoted the formation of C-S-H cementitious material.
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Sample Name | CaO | SiO2 | Al2O3 | MgO | Fe2O3 |
---|---|---|---|---|---|
Fly Ash | 9.25 | 49.55 | 29.37 | 3.23 | 5.33 |
Cement | 51.42 | 24.99 | 8.26 | 3.71 | 4.03 |
Bentonite | 66.7 | — | 28.3 | — | — |
Sample Name | Displacement Volume (%) | Fly Ash (g) | Shield Mud (g) | Cement (g) | Water (g) | Bentonite (g) | Sand (g) | Water–Binder Ratio |
---|---|---|---|---|---|---|---|---|
T1 * | 0 | 230 | 0 | 185 | 254 | 75 | 510 | 0.52 |
A1 | 20% | 184 | 46 | |||||
A2 | 40% | 138 | 92 | |||||
A3 | 60% | 92 | 138 | |||||
A4 | 80% | 46 | 184 | |||||
A5 | 100% | 0 | 230 |
Performance Name | Consistency (cm) | The Loss in Consistency (cm/h) | Slump Diameter (cm) | Slump Loss (cm/h) | Bleeding Rate (%) | Volume Shrinkage (%) | Setting Time (h) | 7-Day Compressive Strength (MPa) | 28-Day Compressive Strength (MPa) |
---|---|---|---|---|---|---|---|---|---|
Performance requirements | 10~13 | <1 | >16 | <2 | ≤3.5 | ≤5 | 4 < h < 6 | ≥3.5 | ≥7 |
Water–Binder Ratio | Water (g) | Cement (g) | Fly Ash (g) | Bentonite (g) | Shield Mud (g) |
---|---|---|---|---|---|
0.52 | 254 | 185 | 46 | 75 | |
0.49 | 240 | 184 | |||
0.46 | 225 | ||||
0.43 | 211 |
Sample Name | Water-Reducing Agent (%) | Water–Binder Ratio | Sand (g) | Water (g) | Binding Material 2 (g) |
---|---|---|---|---|---|
B1 1 | 0.18 | 0.445 | 510 | 218 | 490 |
B2 | 0.21 | ||||
B3 | 0.24 | ||||
B4 | 0.27 |
Sample Name | Binding Material (g) | Sand (g) | Water (g) | Water–Binder Ratio | HEMC (%) | Polycarboxylate Superplasticizer (%) |
---|---|---|---|---|---|---|
T4 | 490 | 510 | 218 | 0.445 | 0.04 | 0.24 |
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Fan, Y.; Gao, Y.; Tao, W.; Huang, S. Study on the Reuse of Shield Mud from Clay Stratum in Synchronous Grouting Slurry. Buildings 2024, 14, 2537. https://doi.org/10.3390/buildings14082537
Fan Y, Gao Y, Tao W, Huang S. Study on the Reuse of Shield Mud from Clay Stratum in Synchronous Grouting Slurry. Buildings. 2024; 14(8):2537. https://doi.org/10.3390/buildings14082537
Chicago/Turabian StyleFan, Ying, Yang Gao, Weilong Tao, and Sihong Huang. 2024. "Study on the Reuse of Shield Mud from Clay Stratum in Synchronous Grouting Slurry" Buildings 14, no. 8: 2537. https://doi.org/10.3390/buildings14082537