Figure 1.
Structural unit model of geopolymer. (The red ball represents oxygen atom, the yellow ball represents the silica atom, and the purple ball represents the aluminum atom).
Figure 1.
Structural unit model of geopolymer. (The red ball represents oxygen atom, the yellow ball represents the silica atom, and the purple ball represents the aluminum atom).
Figure 2.
Particle size distributions of slag.
Figure 2.
Particle size distributions of slag.
Figure 3.
Effect of alkali content on mechanical properties of slag-based geopolymer paste: (a) compressive strength; (b) flexural strength.
Figure 3.
Effect of alkali content on mechanical properties of slag-based geopolymer paste: (a) compressive strength; (b) flexural strength.
Figure 4.
Effect of modulus on mechanical properties of slag-based geopolymer: (a) compressive strength; (b) flexural strength.
Figure 4.
Effect of modulus on mechanical properties of slag-based geopolymer: (a) compressive strength; (b) flexural strength.
Figure 5.
Ion concentration of slag in slurry with large water–slag ratios and different alkali contents: (a) Si4+; (b) Ca2+; (c) Al3+.
Figure 5.
Ion concentration of slag in slurry with large water–slag ratios and different alkali contents: (a) Si4+; (b) Ca2+; (c) Al3+.
Figure 6.
FTIR spectra of slag-based geopolymers prepared with NaOH activators at 28 d with different alkali contents.
Figure 6.
FTIR spectra of slag-based geopolymers prepared with NaOH activators at 28 d with different alkali contents.
Figure 7.
FTIR spectra of paste at 28 d.
Figure 7.
FTIR spectra of paste at 28 d.
Figure 8.
29Si NMR spectra of (a) reference geopolymer paste and (b) geopolymer paste with 0.5% PVA.
Figure 8.
29Si NMR spectra of (a) reference geopolymer paste and (b) geopolymer paste with 0.5% PVA.
Figure 9.
Morphology of (a) reference geopolymer paste, (b) geopolymer paste with 0.5% PVA, and (c) geopolymer paste with 2.0% PVA at 28 d.
Figure 9.
Morphology of (a) reference geopolymer paste, (b) geopolymer paste with 0.5% PVA, and (c) geopolymer paste with 2.0% PVA at 28 d.
Figure 10.
Flexural strength of pastes prepared by pressure-mixing process.
Figure 10.
Flexural strength of pastes prepared by pressure-mixing process.
Figure 11.
Flexural strength of pastes prepared by different curing conditions.
Figure 11.
Flexural strength of pastes prepared by different curing conditions.
Figure 12.
FTIR spectra of pastes prepared by pressure-mixing process with (a) different contents of PVA and (b) different curing regimes at 28 d.
Figure 12.
FTIR spectra of pastes prepared by pressure-mixing process with (a) different contents of PVA and (b) different curing regimes at 28 d.
Figure 13.
29Si NMR spectra of pastes prepared by pressure-mixing process with (a) 1% PVA (normal curing), (b) 3% PVA (normal curing), (c) 5% PVA (normal curing), (d) 3% PVA (dry heat curing), and (e) 3% PVA (steam curing) at 28 d.
Figure 13.
29Si NMR spectra of pastes prepared by pressure-mixing process with (a) 1% PVA (normal curing), (b) 3% PVA (normal curing), (c) 5% PVA (normal curing), (d) 3% PVA (dry heat curing), and (e) 3% PVA (steam curing) at 28 d.
Figure 14.
BSE images of pastes prepared by pressure mixing process with (a) 1% PVA (normal curing), (b) 3% PVA (normal curing), (c) 5% PVA (normal curing), (d) 3% PVA (dry heat curing), and (e) 3% PVA (steam curing) at 28 d.
Figure 14.
BSE images of pastes prepared by pressure mixing process with (a) 1% PVA (normal curing), (b) 3% PVA (normal curing), (c) 5% PVA (normal curing), (d) 3% PVA (dry heat curing), and (e) 3% PVA (steam curing) at 28 d.
Figure 15.
Morphology of pastes prepared by pressure mixing process with (a) 1% PVA (normal curing), (b) 3% PVA (normal curing), (c) 5% PVA (normal curing), (d) 3% PVA (dry heat curing), and (e) 3% PVA (steam curing) at 28 d.
Figure 15.
Morphology of pastes prepared by pressure mixing process with (a) 1% PVA (normal curing), (b) 3% PVA (normal curing), (c) 5% PVA (normal curing), (d) 3% PVA (dry heat curing), and (e) 3% PVA (steam curing) at 28 d.
Figure 16.
(a) Pore size distribution of pastes prepared by different molding processes at 28 d, (b) cumulative pore volume of pastes prepared by different molding processes at 28 d, (c) pore size distribution of pastes prepared by different curing regimes at 28 d, (d) cumulative pore volume of pastes prepared by different curing regimes at 28 d.
Figure 16.
(a) Pore size distribution of pastes prepared by different molding processes at 28 d, (b) cumulative pore volume of pastes prepared by different molding processes at 28 d, (c) pore size distribution of pastes prepared by different curing regimes at 28 d, (d) cumulative pore volume of pastes prepared by different curing regimes at 28 d.
Table 1.
Chemical compositions of slag.
Table 1.
Chemical compositions of slag.
Components (%) | CaO | SiO2 | Al2O3 | MgO | SO3 | Fe2O3 | TiO2 | MnO | LOI |
---|
slag | 37.12 | 32.06 | 14.84 | 10.77 | 1.67 | 1.14 | 0.92 | 0.33 | 1.07 |
Table 2.
Mixture proportions of pastes in weight (%).
Table 2.
Mixture proportions of pastes in weight (%).
Mix ID | Polymer Type | Mix Proportions |
---|
Species | Weight | Water | Slag | BaCl2 | (Na2PO3)6 |
---|
Reference | - | - | 0.35 | 1 | 0.01 | 0.005 |
A1 | PVA | 0.005 | 0.35 | 1 | 0.01 | 0.005 |
A2 | PVA | 0.01 | 0.35 | 1 | 0.01 | 0.005 |
A3 | PVA | 0.02 | 0.35 | 1 | 0.01 | 0.005 |
B1 | PAA-Na | 0.005 | 0.35 | 1 | 0.01 | 0.005 |
B2 | PAA-Na | 0.01 | 0.35 | 1 | 0.01 | 0.005 |
B3 | PAA-Na | 0.02 | 0.35 | 1 | 0.01 | 0.005 |
C1 | CPAM | 0.005 | 0.35 | 1 | 0.01 | 0.005 |
C2 | CPAM | 0.01 | 0.35 | 1 | 0.01 | 0.005 |
C3 | CPAM | 0.02 | 0.35 | 1 | 0.01 | 0.005 |
Table 3.
Mixture proportions for preparing samples in large water–cement ratios.
Table 3.
Mixture proportions for preparing samples in large water–cement ratios.
Alkali Content (%) | NaOH (g) | Slag (g) | Water (g) |
---|
2 | 5.36 | 20 | 70 |
4 | 10.84 | 20 | 70 |
6 | 16.12 | 20 | 70 |
8 | 21.50 | 20 | 70 |
Table 4.
Polymerization distribution and main chain length of slag-based geopolymers prepared with NaOH activators with different alkali contents (28 d): (a) 2% NaOH; (b) 4% NaOH; (c) 6% NaOH; (d) 8% NaOH.
Table 4.
Polymerization distribution and main chain length of slag-based geopolymers prepared with NaOH activators with different alkali contents (28 d): (a) 2% NaOH; (b) 4% NaOH; (c) 6% NaOH; (d) 8% NaOH.
Sample | Qn Cumulative Strength (I/%) |
---|
Q0 | Q1(1Al) | Q1(0Al) | Q2(1Al) | Q2(0Al) | Q3(1Al) | Q3(0Al) | MCL |
---|
(a) | 18.91 | 22.73 | 20.01 | 24.23 | 10.37 | - | 3.75 | 6.12 |
(b) | 16.96 | 23.25 | 20.59 | 25.05 | 9.09 | 3.67 | 1.39 | 6.51 |
(c) | 14.06 | 25.2 | 21.62 | 27.52 | 9.44 | 2.10 | 0.09 | 6.69 |
(d) | 15.30 | 26.56 | 24.19 | 26.86 | 7.09 | - | - | 5.91 |
Table 5.
Degree of polymerization distribution and main chain length of slag-based geopolymers prepared with different modulus activators (28 d): (a) 6%−0.8; (b) 6%−1.2; (c) 6%−1.6; (d) 6%−2.0.
Table 5.
Degree of polymerization distribution and main chain length of slag-based geopolymers prepared with different modulus activators (28 d): (a) 6%−0.8; (b) 6%−1.2; (c) 6%−1.6; (d) 6%−2.0.
Sample | Qn Cumulative Strength (I/%) |
---|
Q0 | Q1(1Al) | Q1(0Al) | Q2(1Al) | Q2(0Al) | Q3(1Al) | Q3(0Al) | MCL |
---|
(a) | 16.45 | 15.44 | 21.33 | 29.53 | 11.60 | 3.68 | 1.97 | 6.81 |
(b) | 13.67 | 17.31 | 18.85 | 26.54 | 15.22 | 5.15 | 2.96 | 7.83 |
(c) | 7.64 | 19.81 | 17.59 | 24.44 | 19.33 | 6.18 | 5.01 | 8.36 |
(d) | 6.53 | 21.89 | 25.24 | - | 36.32 | - | 10.02 | 7.49 |
Table 6.
Effect of polymer type and dosage on compressive and flexural strengths of paste.
Table 6.
Effect of polymer type and dosage on compressive and flexural strengths of paste.
| Compressive Strength (MPa) | Flexural Strength (MPa) |
---|
3 d | 7 d | 28 d | 3 d | 7 d | 28 d |
---|
Reference | 71.8 | 82 | 91 | 5.1 | 6.4 | 7.5 |
A1 | 77.7 | 89.6 | 98.3 | 6.9 | 8.3 | 9.2 |
A2 | 73.1 | 83.4 | 90.3 | 6 | 7.2 | 8.3 |
A3 | 60 | 70.7 | 76.2 | 5.3 | 6.1 | 7.3 |
B1 | 65 | 70.2 | 78.3 | 4.6 | 5.2 | 6.2 |
B2 | 62.4 | 64.3 | 71.5 | 4.4 | 4.9 | 5.8 |
B3 | 58.9 | 60 | 62.5 | 3.7 | 4.5 | 5.3 |
C1 | 63 | 65.6 | 70.9 | 4.8 | 5.9 | 6.6 |
C2 | 57.1 | 59.7 | 63.2 | 4.1 | 5.2 | 6 |
C3 | 51.7 | 57.8 | 60.1 | 4.4 | 4.7 | 5.5 |
Table 7.
Polymerization distribution, main chain length, and reaction degree of paste at 28 d.
Table 7.
Polymerization distribution, main chain length, and reaction degree of paste at 28 d.
PVA Content | Qn Cumulative Strength (I/%) |
---|
Q0 | Q1(1Al) | Q1(0Al) | Q2(1Al) | Q2(0Al) | Q3(1Al) | Q3(0Al) | MCL | α |
---|
0% | 7.64 | 19.81 | 17.59 | 24.44 | 19.33 | 6.18 | 5.01 | 8.36 | 82.85% |
0.5% | 13.98 | 17.77 | 19.22 | 29.31 | 18.85 | - | 0.87 | 8.70 | 73.14% |
Table 8.
Polymerization distribution of pastes prepared by pressure-mixing process under different curing regimes at 28 d.
Table 8.
Polymerization distribution of pastes prepared by pressure-mixing process under different curing regimes at 28 d.
Content Curing Condition | Qn Cumulative Strength (I/%) |
---|
Q0 | Q1(1Al) | Q1(0Al) | Q2(1Al) | Q2(0Al) | Q3(1Al) | Q3(0Al) |
---|
1% | 14.59 | 21.39 | 24.57 | 17.79 | 17.48 | 2.31 | 1.87 |
3% | 19.99 | 16.63 | 22.05 | 18.98 | 27.28 | - | 5.07 |
5% | 21.73 | 18.88 | 19.45 | 20.20 | 15.35 | - | 4.39 |
3% dry | 9.34 | 18.39 | 20.85 | 25.14 | 15.80 | - | 10.03 |
3% steam | 10.07 | 8.99 | 16.91 | 19.50 | 33.72 | - | 10.51 |