Figure 1.
Test setup. (a) Uniaxial compression tests. (b) Triaxial compression tests.
Figure 1.
Test setup. (a) Uniaxial compression tests. (b) Triaxial compression tests.
Figure 2.
The pressure vessel assembly for the triaxial test.
Figure 2.
The pressure vessel assembly for the triaxial test.
Figure 3.
Triaxial stress model of specimen.
Figure 3.
Triaxial stress model of specimen.
Figure 4.
Loading process.
Figure 4.
Loading process.
Figure 5.
The typical cracking patterns. (a) 0 MPa, (b) 3 MPa, (c) 6 MPa, (d) 9 MPa, (e) 12 MPa, (f) 15 MPa, (g) 18 MPa, (h) 21 MPa, (i) 24 MPa, (j) 27 MPa, (k) 30 MPa, (l) uniaxial compression failure modes, (m) oblique-shear failure pattern (σw = 6 MPa), (n) oblique-shear failure pattern (σw = 30 MPa).
Figure 5.
The typical cracking patterns. (a) 0 MPa, (b) 3 MPa, (c) 6 MPa, (d) 9 MPa, (e) 12 MPa, (f) 15 MPa, (g) 18 MPa, (h) 21 MPa, (i) 24 MPa, (j) 27 MPa, (k) 30 MPa, (l) uniaxial compression failure modes, (m) oblique-shear failure pattern (σw = 6 MPa), (n) oblique-shear failure pattern (σw = 30 MPa).
Figure 6.
The stress-strain curves. (a) LAC20, Soak for 1 h, (b) LAC20, Soak for 12 h, (c) LAC30, Soak for 1 h, (d) LAC30, Soak for 12 h, (e) LAC40, Soak for 1 h, (f) LAC40, Soak for 12 h.
Figure 6.
The stress-strain curves. (a) LAC20, Soak for 1 h, (b) LAC20, Soak for 12 h, (c) LAC30, Soak for 1 h, (d) LAC30, Soak for 12 h, (e) LAC40, Soak for 1 h, (f) LAC40, Soak for 12 h.
Figure 7.
Relationship between concrete strength grade and peak stress.
Figure 7.
Relationship between concrete strength grade and peak stress.
Figure 8.
Relationship between compressive strength and lateral confining pressure.
Figure 8.
Relationship between compressive strength and lateral confining pressure.
Figure 9.
The influence of soaking time under the same confining pressure. (a) LAC20, (b) LAC30, (c) LAC40.
Figure 9.
The influence of soaking time under the same confining pressure. (a) LAC20, (b) LAC30, (c) LAC40.
Figure 10.
Failure process of specimens. (a) Failure process of stress-strain curve under uniaxial compression. (b) Failure process of stress-strain curve under triaxial compression (0 MPa < σw ≤ 12 MPa). (c) Failure process of stress-strain curve under triaxial compression (σw > 12 MPa).
Figure 10.
Failure process of specimens. (a) Failure process of stress-strain curve under uniaxial compression. (b) Failure process of stress-strain curve under triaxial compression (0 MPa < σw ≤ 12 MPa). (c) Failure process of stress-strain curve under triaxial compression (σw > 12 MPa).
Figure 11.
The SEM micrographs of ceramsite aggregate concrete. (a) Ceramsite aggregate surface (LAC30-1-0), (b) cement mortar (LAC30-1-0), (c) the interface between ceramsite aggregate and cement mortar (LAC30-1-0). (d) The interface between ceramsite aggregate cross-section and cement mortar (LAC30-1-6). (e) The interface between ceramsite aggregate and cement mortar (LAC30-12-6). (f) The interface between ceramsite aggregate cross-section and cement mortar (LAC30-1-30).
Figure 11.
The SEM micrographs of ceramsite aggregate concrete. (a) Ceramsite aggregate surface (LAC30-1-0), (b) cement mortar (LAC30-1-0), (c) the interface between ceramsite aggregate and cement mortar (LAC30-1-0). (d) The interface between ceramsite aggregate cross-section and cement mortar (LAC30-1-6). (e) The interface between ceramsite aggregate and cement mortar (LAC30-12-6). (f) The interface between ceramsite aggregate cross-section and cement mortar (LAC30-1-30).
Figure 12.
Mohr–Coulomb stress envelope for LAC. (a) LAC20, soak for 1 h; (b) LAC20, soak for 12 h; (c) LAC30, soak for 1 h; (d) LAC30, soak for 12 h; (e) LAC40, soak for 1 h; (f) LAC40, soak for 12 h.
Figure 12.
Mohr–Coulomb stress envelope for LAC. (a) LAC20, soak for 1 h; (b) LAC20, soak for 12 h; (c) LAC30, soak for 1 h; (d) LAC30, soak for 12 h; (e) LAC40, soak for 1 h; (f) LAC40, soak for 12 h.
Figure 13.
Normalized τ-σ diagram.
Figure 13.
Normalized τ-σ diagram.
Figure 14.
Normalized τ-σ curves.
Figure 14.
Normalized τ-σ curves.
Figure 15.
Normalized σ1-σ3 curves.
Figure 15.
Normalized σ1-σ3 curves.
Figure 16.
Uniaxial dimensionless stress-strain curves.
Figure 16.
Uniaxial dimensionless stress-strain curves.
Figure 17.
Comparison of uniaxial compression test curve and fitting curve. (a) LAC20, (b) LAC30, (c) LAC40.
Figure 17.
Comparison of uniaxial compression test curve and fitting curve. (a) LAC20, (b) LAC30, (c) LAC40.
Figure 18.
Triaxial dimensionless stress-strain curves. (a) LAC20, (b) LAC30, (c) LAC40.
Figure 18.
Triaxial dimensionless stress-strain curves. (a) LAC20, (b) LAC30, (c) LAC40.
Figure 19.
Comparison of test curve and fitting curve under different parameters. (a) LAC20, 0 MPa < σw ≤ 6 MPa; (b) LAC20, soak for 1 h, σw > 6 MPa; (c) LAC20, soak for 12 h, σw > 6 MPa; (d) LAC30, soak for 1 h, σw ≤ 3 MPa; (e) LAC30, soak for 12 h, σw ≤ 3 MPa; (f) LAC30, 3 MPa < σw ≤ 9 MPa; (g) LAC30, soak for 1 h, σw > 9 MPa; (h) LAC30, soak for 12 h, σw > 9 MPa; (i) LAC40, soak for 1 h, σw ≤ 3 MPa; (j) LAC40, soak for 12 h, σw ≤ 3 MPa; (k) LAC40, 3 MPa < σw ≤ 9 MP; (l) LAC40, σw > 9 MP.
Figure 19.
Comparison of test curve and fitting curve under different parameters. (a) LAC20, 0 MPa < σw ≤ 6 MPa; (b) LAC20, soak for 1 h, σw > 6 MPa; (c) LAC20, soak for 12 h, σw > 6 MPa; (d) LAC30, soak for 1 h, σw ≤ 3 MPa; (e) LAC30, soak for 12 h, σw ≤ 3 MPa; (f) LAC30, 3 MPa < σw ≤ 9 MPa; (g) LAC30, soak for 1 h, σw > 9 MPa; (h) LAC30, soak for 12 h, σw > 9 MPa; (i) LAC40, soak for 1 h, σw ≤ 3 MPa; (j) LAC40, soak for 12 h, σw ≤ 3 MPa; (k) LAC40, 3 MPa < σw ≤ 9 MP; (l) LAC40, σw > 9 MP.
Table 1.
Physical properties of ceramsite aggregate.
Table 1.
Physical properties of ceramsite aggregate.
Type | Fly Ash Content | Bulk Density (kg/m3) | Numerical Tube Pressure (MPa) | 1 h Water Absorption | 12 h Water Absorption | Saturated Water Absorption |
---|
Fly ash ceramsite | 80% | 650 | 7.2 | 14.96% | 16.12% | 17.22% |
Table 2.
Mix proportion of lightweight aggregate concrete.
Table 2.
Mix proportion of lightweight aggregate concrete.
Concrete Strength | Cement (kg/m3) | Ceramsite (kg/m3) | Sand (kg/m3) | Fly Ash (kg/m3) | Water (kg/m3) | Water-Cement Ratio |
---|
LAC20 | 350 | 420.3 | 667.4 | 75 | 170 | 0.40 |
LAC30 | 400 | 407.7 | 634.3 | 47.4 | 170 | 0.38 |
LAC40 | 450 | 392 | 609.7 | 22.2 | 170 | 0.36 |
Table 3.
Parameters of specimens.
Table 3.
Parameters of specimens.
Specimen ID | Concrete Strength (MPa) | Soaking Time (h) | Confining Pressure (Mpa) | Specimen ID | Concrete Strength (Mpa) | Soaking Time (h) | Confining Pressure (Mpa) |
---|
LAC20-1-0 | 20 | 1 | 0 | LAC30-1-30 | 30 | 1 | 30 |
LAC20-1-6 | 20 | 1 | 6 | LAC30-1-33 | 30 | 1 | 33 |
LAC20-1-12 | 20 | 1 | 12 | LAC30-12-0 | 30 | 12 | 0 |
LAC20-1-18 | 20 | 1 | 18 | LAC30-12-3 | 30 | 12 | 3 |
LAC20-1-24 | 20 | 1 | 24 | LAC30-12-6 | 30 | 12 | 6 |
LAC20-1-30 | 20 | 1 | 30 | LAC30-12-9 | 30 | 12 | 9 |
LAC20-1-36 | 20 | 1 | 36 | LAC30-12-12 | 30 | 12 | 12 |
LAC20-1-42 | 20 | 1 | 42 | LAC30-12-15 | 30 | 12 | 15 |
LAC20-12-0 | 20 | 12 | 0 | LAC30-12-18 | 30 | 12 | 18 |
LAC20-12-6 | 20 | 12 | 6 | LAC30-12-21 | 30 | 12 | 21 |
LAC20-12-12 | 20 | 12 | 12 | LAC30-12-24 | 30 | 12 | 24 |
LAC20-12-18 | 20 | 12 | 18 | LAC30-12-27 | 30 | 12 | 27 |
LAC20-12-24 | 20 | 12 | 24 | LAC30-12-30 | 30 | 12 | 30 |
LAC20-12-30 | 20 | 12 | 30 | LAC30-12-33 | 30 | 12 | 33 |
LAC20-12-36 | 20 | 12 | 36 | LAC40-1-0 | 40 | 1 | 0 |
LAC20-12-42 | 20 | 12 | 42 | LAC40-1-3 | 40 | 1 | 3 |
LAC30-1-0 | 30 | 1 | 0 | LAC40-1-6 | 40 | 1 | 6 |
LAC30-1-3 | 30 | 1 | 3 | LAC40-1-9 | 40 | 1 | 9 |
LAC30-1-6 | 30 | 1 | 6 | LAC40-1-12 | 40 | 1 | 12 |
LAC30-1-9 | 30 | 1 | 9 | LAC40-1-15 | 40 | 1 | 15 |
LAC30-1-12 | 30 | 1 | 12 | LAC40-12-0 | 40 | 12 | 0 |
LAC30-1-15 | 30 | 1 | 15 | LAC40-12-3 | 40 | 12 | 3 |
LAC30-1-18 | 30 | 1 | 18 | LAC40-12-6 | 40 | 12 | 6 |
LAC30-1-21 | 30 | 1 | 21 | LAC40-12-9 | 40 | 12 | 9 |
LAC30-1-24 | 30 | 1 | 24 | LAC40-12-12 | 40 | 12 | 12 |
LAC30-1-27 | 30 | 1 | 27 | LAC40-12-15 | 40 | 12 | 15 |
Table 4.
Mechanical properties of test specimens.
Table 4.
Mechanical properties of test specimens.
Specimen | σu/Mpa | Specimen | σu/Mpa | Specimen | σu/Mpa |
---|
LAC20-1-00 | 18.10 | LAC30-1-00 | 19.03 | LAC30-12-18 | 93.88 |
LAC20-1-06 | 54.30 | LAC30-1-03 | 44.43 | LAC30-12-21 | 108.49 |
LAC20-1-12 | 75.92 | LAC30-1-06 | 56.01 | LAC30-12-24 | 115.76 |
LAC20-1-18 | 101.93 | LAC30-1-09 | 64.34 | LAC30-12-27 | 126.55 |
LAC20-1-24 | 115.61 | LAC30-1-12 | 77.45 | LAC30-12-30 | 136.52 |
LAC20-1-30 | 133.65 | LAC30-1-15 | 87.76 | LAC30-12-33 | 140.43 |
LAC20-1-36 | 151.90 | LAC30-1-18 | 93.79 | LAC40-1-00 | 29.27 |
LAC20-1-42 | 167.17 | LAC30-1-21 | 100.36 | LAC40-1-03 | 44.55 |
LAC20-12-00 | 18.09 | LAC30-1-24 | 114.11 | LAC40-1-06 | 58.26 |
LAC20-12-06 | 54.29 | LAC30-1-27 | 115.75 | LAC40-1-09 | 65.95 |
LAC20-12-12 | 73.64 | LAC30-1-30 | 130.57 | LAC40-1-12 | 76.98 |
LAC20-12-18 | 92.25 | LAC30-1-33 | 138.43 | LAC40-1-15 | 88.06 |
LAC20-12-24 | 109.49 | LAC30-12-00 | 22.11 | LAC40-12-00 | 28.07 |
LAC20-12-30 | 131.77 | LAC30-12-03 | 46.83 | LAC40-12-03 | 50.26 |
LAC20-12-36 | 145.72 | LAC30-12-06 | 59.02 | LAC40-12-06 | 61.84 |
LAC20-12-42 | 162.35 | LAC30-12-09 | 71.25 | LAC40-12-09 | 70.09 |
| | LAC30-12-12 | 79.02 | LAC40-12-12 | 76.73 |
| | LAC30-12-15 | 88.91 | LAC40-12-15 | 91.65 |
Table 5.
Fitting coefficient of constitutive relation under triaxial compression.
Table 5.
Fitting coefficient of constitutive relation under triaxial compression.
Curve Branch | Confining Pressure Value | Fit Coefficient |
---|
Ascending Curve | 0 MPa < σw ≤ 3 MPa | α = 1.712 |
3 MPa < σw ≤ 9 MP | α = 2.043 |
σw > 9 MPa | α = 3.120 |
descending branch | 0 MPa < σw ≤ 3 MPa | β = 0.32 T + 0.548 (T = 1, 12) |
3 MPa < σw ≤ 9 MP | β = 0.474 |
σw > 9 MPa | descending branch |