Fluidity and Strength of Loess-Based Quick Consolidated Backfill Material with One High-Water Content
Abstract
:1. Introduction
2. Orthogonal Test Schemes and Test Results
2.1. Experimental Raw Material Analysis
2.2. Experimental Scheme Design
2.3. Experimental Procedure
- (1)
- Brush the inner surface of the three-gang mold with lubricating oil before the experiment to ensure that the test piece is relatively intact after demolding;
- (2)
- Weigh the corresponding mass of raw materials according to Table 2, and mix them with water in the mixing bucket;
- (3)
- Pour out some mixed materials and perform initial setting time testing in the beaker. When the beaker is tilted at 45°, there is no obvious flow trace of the material in the cup, which is considered the initial setting of the material (Figure 2a);
- (4)
- Conduct the flow spread test on a smooth glass plate. Apply butter to the bottom of the flow spread cylinder and place it on the glass plate. Pour the mixed filling material into the cylinder to two-thirds of the total height, lift the cylinder and measure the material spread using a tape measure (Figure 2b);
- (5)
- After the material is mixed, it is poured into the standard mold, appropriately vibrated to eliminate air bubbles in the slurry, and stands for three days. Using an air gun to demold the test piece, the demolded specimen is placed in a constant temperature and humidity curing box for curing (Figure 2c,d);
- (6)
- After curing, the specimen is placed on the MTS electro-hydraulic servo-motor machine for the direct shear and uniaxial compressive tests (Figure 2f,g).
3. Significance Analysis of Fluidity
3.1. Factors Influencing the Initial Setting Time
3.2. Factors Influencing the Diffusivity
4. Significance Analysis of Strength
4.1. Factors Influencing the Compressive Strength
4.2. Factors Influencing the Shear Strength
5. Analytical Model for Characteristic Parameters of Fluidity and Strength
5.1. Changes in Characteristic Parameters under Influences of Each Single Factor
5.2. Analytical Model of Characteristic Parameters
6. Conclusions
- (i).
- By conducting orthogonal tests, taking the mass concentration of loess water, the content of high-water-content materials, the cement content, and the content of fly ash as four factors, for each of which four levels were set, sixteen groups of mix designs were tested. After testing the fluidity and strength characteristics, the analysis revealed that the initial setting time, diffusivity, compressive strength, and shear strength of the loess material were distributed in ranges of 13~33 min, 400~580 mm, 0.917~3.605 MPa, and 0.360~0.722 MPa, respectively;
- (ii).
- For the initial setting time, the four factors were listed in descending order as A > D > B > C, wherein all four factors showed lower significance. The four factors were ranked such that A > B > C > D according to their influences on the diffusivity, indicative of the mass concentration of loess water being the main factor influencing the diffusivity. With regard to the compressive strength, the four factors were ranked such that A > C > D > B, implying that the mass concentration of loess water and the cement content were the main factors influencing the uniaxial compressive strength. The four factors were ranked such that A > C > D > B according to their influences on the shear strength, which means that the mass concentration of loess water and the content of cement were the main factors influencing the shear strength;
- (iii).
- Mathematical relationships of factors A, B, C, and D with the fluidity and strength indices were fitted.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Number of Level Groups | A. Loess Mass Concentration | B. High-Water Content | C. Cement Content | D. Fly Ash Content |
---|---|---|---|---|
1 | 140:260 (concentration 35.00%) | 12 | 28 | 20 |
2 | 160:240 (concentration 40.00%) | 16 | 34 | 25 |
3 | 180:220 (concentration 45.00%) | 20 | 40 | 30 |
4 | 200:200 (concentration 50.00%) | 24 | 46 | 35 |
Number of Experimental Groups | Influencing Factors | Test Results | |||||||
---|---|---|---|---|---|---|---|---|---|
A | B | C | D | Initial Coagulation Time/min | Diffusion /mm | Compressive Strength/MPa | Shear Strength/MPa | Overall Rating | |
1 | 0.35 | 12 | 28 | 20 | 28.00 | 58.00 | 2.13 | 0.41 | 22.135 |
2 | 0.35 | 16 | 34 | 25 | 28.00 | 56.70 | 1.39 | 0.43 | 21.630 |
3 | 0.35 | 20 | 40 | 30 | 16.00 | 56.30 | 1.93 | 0.40 | 18.658 |
4 | 0.35 | 24 | 46 | 35 | 17.00 | 47.80 | 1.85 | 0.48 | 16.783 |
5 | 0.40 | 12 | 34 | 30 | 13.00 | 51.00 | 1.29 | 0.51 | 16.450 |
6 | 0.40 | 16 | 28 | 35 | 23.00 | 53.70 | 1.07 | 0.41 | 19.545 |
7 | 0.40 | 20 | 46 | 20 | 17.00 | 49.30 | 1.71 | 0.62 | 17.158 |
8 | 0.40 | 24 | 40 | 25 | 17.00 | 47.70 | 1.25 | 0.46 | 16.603 |
9 | 0.45 | 12 | 40 | 35 | 33.00 | 45.70 | 1.73 | 0.50 | 20.233 |
10 | 0.45 | 16 | 46 | 30 | 18.00 | 48.70 | 2.42 | 0.50 | 17.405 |
11 | 0.45 | 20 | 28 | 25 | 20.00 | 46.70 | 0.92 | 0.36 | 16.995 |
12 | 0.45 | 24 | 34 | 20 | 20.00 | 43.30 | 2.40 | 0.47 | 16.543 |
13 | 0.50 | 12 | 46 | 25 | 15.00 | 41.20 | 2.65 | 0.72 | 14.893 |
14 | 0.50 | 16 | 40 | 20 | 17.00 | 42.30 | 3.03 | 0.66 | 15.748 |
15 | 0.50 | 20 | 34 | 35 | 18.00 | 40.20 | 3.61 | 0.64 | 15.613 |
16 | 0.50 | 24 | 28 | 30 | 13.00 | 40.70 | 1.62 | 0.59 | 13.978 |
Factor | Initial Coagulation Time/min | Diffusion/mm | ||||||||||
A | B | C | D | A | B | C | D | |||||
k1 | 22.250 | 22.2500 | 21 | 20.5 | 54.70 | 48.976 | 49.77 | 48.23 | ||||
k2 | 17.500 | 21.5000 | 19.75 | 20 | 50.42 | 50.35 | 47.80 | 48.08 | ||||
k3 | 22.750 | 17.7500 | 20.75 | 15 | 46.10 | 48.13 | 48.00 | 49.18 | ||||
k4 | 15.750 | 16.7500 | 16.75 | 22.75 | 41.10 | 44.86 | 46.75 | 46.85 | ||||
R | 7 | 5.5 | 4.25 | 7.75 | 13.60 | 5.48 | 3.02 | 2.33 | ||||
Factor | Compressive Strength/MPa | Shear Strength/MPa | Overall Rating | |||||||||
A | B | C | D | A | B | C | D | A | B | C | D | |
k1 | 1.8235 | 1.9492 | 1.4332 | 2.3140 | 0.4303 | 0.5355 | 0.4405 | 0.5385 | 19.801 | 18.428 | 18.161 | 17.896 |
k2 | 1.330 | 1.980 | 2.1710 | 1.5532 | 0.5005 | 0.4980 | 0.5142 | 0.4938 | 17.438 | 18.582 | 17.559 | 17.532 |
k3 | 1.8660 | 2.0390 | 1.9855 | 1.8142 | 0.4572 | 0.5048 | 0.5053 | 0.4990 | 17.793 | 17.106 | 17.810 | 16.623 |
k4 | 2.7260 | 1.7773 | 2.1557 | 2.0640 | 0.6515 | 0.5013 | 0.5795 | 0.5082 | 15.057 | 15.972 | 16.559 | 18.043 |
R | 1.3960 | 0.2617 | 0.7378 | 0.7607 | 0.2212 | 0.0375 | 0.139 | 0.0448 | 5.554 | 2.820 | 2.037 | 2.721 |
Source of Variation | Sum of Squared Deviations | Degree of Freedom | Variance | F-Value | Fα | Significance Level |
---|---|---|---|---|---|---|
A | 144.688 | 3 | 48.229 | F0.01(3,15) = 5.417 F0.05(3,15) = 3.287 F0.10(3,15) = 2.490 F0.25(3,15) = 1.520 | --- | |
B | 88.688 | 3 | 29.563 | --- | ||
C | 45.688 | 3 | 15.229 | --- | ||
D | 128.188 | 3 | 42.729 | --- | ||
Error e | 78.688 | 3 | 26.229 | |||
Correct errors e | 485.938 | 15 | 32.396 | |||
Sum | 485.938 |
Source of Variation | Sum of Squared Deviations | Degree of Freedom | Variance | F-Value | Fα | Significance Level |
---|---|---|---|---|---|---|
A | 93.847 | 3 | 31.282 | 3.324 | F0.01(3,3) = 29.457 F0.05(3,3) = 9.277 F0.10(3,3) = 5.391 F0.25(3,3) = 2.356 | o |
B | 205.445 | 3 | 68.482 | 7.278 | * | |
C | 96.573 | 3 | 32.191 | 3.421 | o | |
D | 82.922 | 3 | 27.641 | 2.937 | o | |
Error e | 28.229 | 3 | 9.410 | |||
Sum | 507.017 |
Source of Variation | Sum of Squared Deviations | Degree of Freedom | Variance | F-Value | Fα | Significance Level |
---|---|---|---|---|---|---|
A | 4.036 | 3 | 1.3452 | 3.932 | F0.01(3,12) = 5.953 F0.05(3,12) = 3.490 F0.10(3,12) = 2.606 F0.25(3,12) = 1.561 | ** |
B | 0.152 | 3 | 0.0505 | --- | ||
C | 1.434 | 3 | 0.4778 | --- | ||
D | 1.281 | 3 | 0.4270 | --- | ||
Error e | 1.240 | 3 | 0.4133 | |||
Correct errors e | 4.106 | 12 | 0.3422 | |||
Sum | 8.141 |
Source of Variation | Sum of Squared Deviations | Degree of Freedom | Variance | F-Value | Fα | Significance Level |
---|---|---|---|---|---|---|
A | 0.1170 | 3 | 0.0390 | 30.974 | F0.01(3,9) = 6.992 F0.05(3,9) = 3.863 F0.10(3,9) = 2.813 F0.25(3,9) = 1.632 | *** |
C | 0.0040 | 3 | 0.0013 | --- | ||
D | 0.0388 | 3 | 0.0129 | 10.271 | *** | |
0.0048 | 3 | 0.0016 | --- | |||
Error e | 0.0025 | 3 | 0.0008 | |||
Correct errors e | 0.0113 | 9 | 0.0013 | |||
Sum | 0.1670 |
Factor | Index | Fitted Relationship | General Formula | Degree of Fit R2 |
---|---|---|---|---|
Yellow mud quality Concentration (PA) | Initial coagulation time | 0.92 | ||
Diffusion | 0.98 | |||
Compressive strength | 0.99 | |||
Tensile strength | 0.99 | |||
High-water content (PB) | Initial coagulation time | 0.96 | ||
Diffusion | 0.99 | |||
Compressive strength | 0.99 | |||
Tensile strength | 0.99 | |||
Cement content (PC) | Initial coagulation time | 0.99 | ||
Diffusion | 0.99 | |||
Compressive strength | 0.99 | |||
Tensile strength | 0.99 | |||
Fly ash content (PD) | Initial coagulation time | 0.99 | ||
Diffusion | 0.99 | |||
Compressive strength | 0.99 | |||
Tensile strength | 0.99 |
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Cui, C.; An, B.; Cui, H.; Yi, Q.; Wang, J. Fluidity and Strength of Loess-Based Quick Consolidated Backfill Material with One High-Water Content. Materials 2023, 16, 5544. https://doi.org/10.3390/ma16165544
Cui C, An B, Cui H, Yi Q, Wang J. Fluidity and Strength of Loess-Based Quick Consolidated Backfill Material with One High-Water Content. Materials. 2023; 16(16):5544. https://doi.org/10.3390/ma16165544
Chicago/Turabian StyleCui, Chenghao, Baifu An, Heng Cui, Qiaomei Yi, and Jiale Wang. 2023. "Fluidity and Strength of Loess-Based Quick Consolidated Backfill Material with One High-Water Content" Materials 16, no. 16: 5544. https://doi.org/10.3390/ma16165544
APA StyleCui, C., An, B., Cui, H., Yi, Q., & Wang, J. (2023). Fluidity and Strength of Loess-Based Quick Consolidated Backfill Material with One High-Water Content. Materials, 16(16), 5544. https://doi.org/10.3390/ma16165544