Author Contributions
Conceptualization, W.X.; methodology, X.T.; validation, W.X. and X.T.; investigation, X.T.; data curation, X.T.; writing—original draft preparation, X.T.; writing—review and editing, X.T.; supervision, supervision, W.X.; project administration, W.X.; funding acquisition, W.X. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Several cases of acoustic wave transmitting in CTB specimen.
Figure 1.
Several cases of acoustic wave transmitting in CTB specimen.
Figure 2.
Particle size distribution of the tailings samples used in the tests.
Figure 2.
Particle size distribution of the tailings samples used in the tests.
Figure 3.
Acoustic wave testing of specimens.
Figure 3.
Acoustic wave testing of specimens.
Figure 4.
UPV development of CTB with different: (a) solid content of 72%; (b) solid content of 75% (c) solid content of 78%.
Figure 4.
UPV development of CTB with different: (a) solid content of 72%; (b) solid content of 75% (c) solid content of 78%.
Figure 5.
MIP test results for samples with different b/w ratios and solid content (a) cumulative pore volume; (b) pore size distribution.
Figure 5.
MIP test results for samples with different b/w ratios and solid content (a) cumulative pore volume; (b) pore size distribution.
Figure 6.
Development of DEM of CTB samples: (a) DEM, solid content of 72%; (b) DEM, solid content of 75% (c) DEM, solid content of 78%.
Figure 6.
Development of DEM of CTB samples: (a) DEM, solid content of 72%; (b) DEM, solid content of 75% (c) DEM, solid content of 78%.
Figure 7.
Development of DSM of CTB samples: (a) DSM, solid content of 72%; (b) DSM, solid content of 75% (c) DSM, solid content of 78%.
Figure 7.
Development of DSM of CTB samples: (a) DSM, solid content of 72%; (b) DSM, solid content of 75% (c) DSM, solid content of 78%.
Figure 8.
The UCS of CTB under the same solid content during the curing age of 28 days: (a) solid content of 72%; (b) solid content of 75% (c) solid content of 78%.
Figure 8.
The UCS of CTB under the same solid content during the curing age of 28 days: (a) solid content of 72%; (b) solid content of 75% (c) solid content of 78%.
Figure 9.
SEM images of samples with different solid content. (a) b/w ratio of 1:8, solid content of 72%, curing time of 3 d; (b) b/w ratio of 1:8, solid content of 72%, curing time of 7 d; (c) b/w ratio of 1:8, solid content of 72%, curing time of 28 d.
Figure 9.
SEM images of samples with different solid content. (a) b/w ratio of 1:8, solid content of 72%, curing time of 3 d; (b) b/w ratio of 1:8, solid content of 72%, curing time of 7 d; (c) b/w ratio of 1:8, solid content of 72%, curing time of 28 d.
Figure 10.
SEM images of samples with different solid content. (a) b/w ratio of 1:4, solid content of 72%, curing time of 7 d; (b) b/w ratio of 1:8, solid content of 72%, curing time of 7 d; (c) b/w ratio of 1:10, solid content of 72%, curing time of 7 d.
Figure 10.
SEM images of samples with different solid content. (a) b/w ratio of 1:4, solid content of 72%, curing time of 7 d; (b) b/w ratio of 1:8, solid content of 72%, curing time of 7 d; (c) b/w ratio of 1:10, solid content of 72%, curing time of 7 d.
Figure 11.
SEM images of samples with different solid content. (a) b/w ratio of 1:4, solid content of 72%, curing time of 7 d; (b) b/w o of 1:4, solid content of 75%,curing time of 7 d; (c) b/w of 1:4, solid content of 78%, curing time of 7 d.
Figure 11.
SEM images of samples with different solid content. (a) b/w ratio of 1:4, solid content of 72%, curing time of 7 d; (b) b/w o of 1:4, solid content of 75%,curing time of 7 d; (c) b/w of 1:4, solid content of 78%, curing time of 7 d.
Figure 12.
Relationship between UCS and UPV of CTB.
Figure 12.
Relationship between UCS and UPV of CTB.
Table 1.
Chemical component of unclassified tailings.
Table 1.
Chemical component of unclassified tailings.
Composition | Content | Composition | Content | Composition | Content |
---|
SiO2 | 79.770% | MgO | 2.040% | H2O | 0.061% |
Al2O3 | 2.540% | Cao | 2.780% | TiO2 | 0.098% |
Fe2O3 | 8.040% | Na2O | 0.310% | P2O5 | 0.050% |
FeO | 1.160% | K2O | 0.670% | MnO | 0.013% |
Table 2.
Main chemical composition of the binders used for CTB preparation.
Table 2.
Main chemical composition of the binders used for CTB preparation.
Type | MgO (%) | CaO (%) | SiO2 (%) | Al2O3 (%) | Fe2O3 (%) | SO3 (%) | Relative Density | Specific Surface (m2/g) |
---|
PCI | 2.65 | 62.82 | 18.03 | 4.53 | 2.70 | 3.82 | 3.10 | 1.30 |
Table 3.
Main physical and chemical characteristics of the binders used.
Table 3.
Main physical and chemical characteristics of the binders used.
Element (unit) | Sp (m2/g) | Gs (-) | S (wt%) | Ca (wt%) | Si (wt%) | Al (wt%) | Mg (wt%) | Fe (wt%) | Si/Ca |
---|
PCI | 1.32 | 3.15 | 1.5 | 44.9 | 8.4 | 2.4 | 1.6 | 1.9 | 0.2 |
Table 4.
The paste proportions for tests.
Table 4.
The paste proportions for tests.
Sample No. | Curing Temperature | Curing Time (days) | Binder-to-Water Ratio (w/c) | Solid Content/% | Number of Samples |
---|
C472 | 25 °C | 3, 7, 28 | 1/4 | 72% | 10 |
C475 | 25 °C | 3, 7, 28 | 1/4 | 75% | 10 |
C478 | 25 °C | 3, 7, 28 | 1/4 | 78% | 10 |
C672 | 25 °C | 3, 7, 28 | 1/6 | 72% | 10 |
C675 | 25 °C | 3, 7, 28 | 1/6 | 75% | 10 |
C678 | 25 °C | 3, 7, 28 | 1/6 | 78% | 10 |
C872 | 25 °C | 3, 7, 28 | 1/8 | 72% | 10 |
C875 | 25 °C | 3, 7, 28 | 1/8 | 75% | 10 |
C878 | 25 °C | 3, 7, 28 | 1/8 | 78% | 10 |
C1072 | 25 °C | 3, 7, 28 | 1/10 | 72% | 10 |
C1075 | 25 °C | 3, 7, 28 | 1/10 | 75% | 10 |
C1078 | 25 °C | 3, 7, 28 | 1/10 | 78% | 10 |
Table 5.
Strength increment rates of CTB samples within different curing times.
Table 5.
Strength increment rates of CTB samples within different curing times.
Sample No. | UCS /MPa | Increment Values /MPa | Increment Rate of UCS /(MPa·day−1) |
---|
3 d | 7 d | 28 d | 0–3 d | 3–7 d | 7–28 d | 0–3 d | 3–7 d | 7–28 d |
---|
C472 | 0.6 | 1.4 | 2.5 | 0.6 | 0.8 | 1.1 | 0.20 | 0.20 | 0.05 |
C672 | 0.4 | 0.8 | 2.1 | 0.4 | 0.4 | 1.3 | 0.13 | 0.10 | 0.06 |
C872 | 0.35 | 0.4 | 1.4 | 0.35 | 0.05 | 1.0 | 0.11 | 0.01 | 0.05 |
C1072 | 0.25 | 0.3 | 1.0 | 0.25 | 0.05 | 0.7 | 0.08 | 0.01 | 0.03 |
C475 | 0.9 | 2.1 | 3.9 | 0.9 | 1.2 | 1.8 | 0.30 | 0.30 | 0.08 |
C675 | 0.5 | 1.3 | 3.5 | 0.5 | 0.8 | 3 | 0.17 | 0.20 | 0.14 |
C875 | 0.4 | 0.7 | 1.8 | 0.4 | 0.3 | 1.4 | 0.13 | 0.08 | 0.07 |
C1075 | 0.3 | 0.6 | 1.1 | 0.3 | 0.3 | 0.5 | 0.10 | 0.08 | 0.02 |
C478 | 1.1 | 3.0 | 5.0 | 1.1 | 1.9 | 2 | 0.37 | 0.48 | 0.10 |
C678 | 0.6 | 1.9 | 3.8 | 0.6 | 1.3 | 1.9 | 0.20 | 0.33 | 0.09 |
C878 | 0.5 | 1.4 | 2.4 | 0.5 | 0.9 | 1 | 0.17 | 0.23 | 0.05 |
C1078 | 0.4 | 0.7 | 1.3 | 0.4 | 0.3 | 0.6 | 0.13 | 0.08 | 0.03 |
Table 6.
Correlation between UPV and UCS.
Table 6.
Correlation between UPV and UCS.
Sample No. | UCS Equation Exponent (y = c + a·ebx ) | Correlation Coefficient (r) | Equation Number |
---|
C472 | | 0.9478 | 1 |
C672 | | 0.99 | 2 |
C872 | | 0.984 | 3 |
C1072 | | 0.996 | 4 |
C475 | | 0.975 | 5 |
C675 | | 0.89 | 6 |
C875 | | 0.914 | 7 |
C1075 | | 0.911 | 8 |
C478 | | 0.897 | 9 |
C678 | | 0.8735 | 10 |
C878 | | 0.989 | 11 |
C1078 | | 0.964 | 12 |
Table 7.
Results of t and F tests for the correlation between the UCS and UPV.
Table 7.
Results of t and F tests for the correlation between the UCS and UPV.
Sample No. | tcomputed | ttabulated | Fcomputed | Ftabulated | Equation Number |
---|
C472 | 8.4 | ±1.833 | 119.06 | ±3.18 | 1 |
C672 | 19.84 | ±1.833 | 263.5 | ±3.18 | 2 |
C872 | 15.62 | ±1.833 | 299.18 | ±3.18 | 3 |
C1072 | 31.52 | ±1.833 | 159 | ±3.18 | 4 |
C475 | 12.41 | ±1.833 | 155.2 | ±3.18 | 5 |
C675 | 5.52 | ±1.833 | 53.5 | ±3.18 | 6 |
C875 | 6.37 | ±1.833 | 53.9 | ±3.18 | 7 |
C1075 | 6.24 | ±1.833 | 75.2 | ±3.18 | 8 |
C478 | 5.73 | ±1.833 | 61.47 | ±3.18 | 9 |
C678 | 5.07 | ±1.833 | 36.55 | ±3.18 | 10 |
C878 | 18.91 | ±1.833 | 550 | ±3.18 | 11 |
C1078 | 10.25 | ±1.833 | 207.3 | ±3.18 | 12 |