1 Introduction
2 Research Significance
3 Experimental Investigation
3.1 Materials
3.1.1 Physical Properties
Material | Provider | Chemical composition | Specific gravity | Retained on #325 sieve |
---|---|---|---|---|
Class C fly ash | Boral Material Technologies | >80 % CaAl2Si2O8 | 2.65 | 11 % |
<15 % Fe2MgO4 | ||||
<5 % Na2K2SO5 | ||||
NaOH pellets | Fisher Scientific | >95 % NaOH | 2.13 | – |
<3 % Na2CO3 | ||||
Na2SiO3 solution | PQ Corporation | 14.7 % Na2O | 1.53 | – |
29.4 % SiO2 | ||||
55.9 % H2O |
Material | Oven dry specific gravity | Saturated surface dry specific gravity | Absorption | Fineness modulus |
---|---|---|---|---|
Limestone sand | 2.46 | 2.57 | 4.6 % | 2.91 |
3.1.2 Characterization
Element | Fly ash | Geopolymer | ||
---|---|---|---|---|
Weight (%) | Atomic (%) | Weight (%) | Atomic (%) | |
O | 43.98 | 62.06 | 43.89 | 59.15 |
Na | 1.71 | 1.68 | 15.06 | 14.13 |
Mg | 2.67 | 2.48 | 1.61 | 1.43 |
Al | 9.64 | 8.07 | 7.10 | 5.68 |
Si | 10.48 | 8.42 | 11.14 | 8.55 |
P | 1.19 | 0.86 | 0.82 | 0.57 |
S | 1.05 | 0.74 | 0.62 | 0.42 |
K | 0.32 | 0.19 | 0.31 | 0.17 |
Ca | 23.21 | 13.07 | 15.35 | 8.26 |
Ti | 1.47 | 0.69 | 1.05 | 0.47 |
Fe | 4.29 | 1.73 | 3.06 | 1.18 |
3.2 Specimens
# | NaOH:fly ash ratio | Na2SiO3:fly ash ratio | Sand:fly ash ratio | Fly ash (kg/m3) | Limestone sand (kg/m3) | H2O (kg/m3) | NaOH pellets (kg/m3) | Na2SiO3 solution (kg/m3) |
---|---|---|---|---|---|---|---|---|
1 | 0.050 | 0.025 | 1.0 | 720 | 720 | 337 | 36 | 41 |
2 | 0.050 | 0.050 | 1.0 | 720 | 720 | 314 | 36 | 82 |
3 | 0.050 | 0.075 | 1.0 | 720 | 720 | 292 | 36 | 122 |
4 | 0.050 | 0.100 | 1.0 | 720 | 720 | 269 | 36 | 163 |
5 | 0.075 | 0.025 | 1.0 | 720 | 720 | 337 | 54 | 41 |
6 | 0.075 | 0.050 | 1.0 | 720 | 720 | 314 | 54 | 82 |
7 | 0.075 | 0.075 | 1.0 | 720 | 720 | 292 | 54 | 122 |
8 | 0.075 | 0.100 | 1.0 | 720 | 720 | 269 | 54 | 163 |
9 | 0.100 | 0.025 | 1.0 | 720 | 720 | 337 | 72 | 41 |
10 | 0.100 | 0.050 | 1.0 | 720 | 720 | 314 | 72 | 82 |
11 | 0.100 | 0.075 | 1.0 | 720 | 720 | 292 | 72 | 122 |
12 | 0.100 | 0.100 | 1.0 | 720 | 720 | 269 | 72 | 163 |
13 | 0.125 | 0.025 | 1.0 | 720 | 720 | 337 | 90 | 41 |
14 | 0.125 | 0.050 | 1.0 | 720 | 720 | 314 | 90 | 82 |
15 | 0.125 | 0.075 | 1.0 | 720 | 720 | 292 | 90 | 122 |
16 | 0.125 | 0.100 | 1.0 | 720 | 720 | 269 | 90 | 163 |
17 | 0.100 | 0.100 | 1.5 | 630 | 945 | 235 | 63 | 143 |
18 | 0.100 | 0.100 | 2.0 | 560 | 1,120 | 209 | 56 | 127 |
19 | 0.100 | 0.100 | 2.5 | 500 | 1,250 | 187 | 50 | 113 |
20 | 0.100 | 0.100 | 3.0 | 450 | 1,350 | 168 | 45 | 102 |
3.3 Procedures
3.3.1 Mixing, Casting and Curing
3.3.2 Fresh Property Tests
3.3.3 Hardened Property Tests
3.4 Analytical Techniques
4 Experimental Results
# | NaOH:fly ash ratio | Na2SiO3:fly ash ratio | Sand:fly ash ratio | Temperature (°C) | Flow (%) | Fresh density (kg/m3) |
---|---|---|---|---|---|---|
1 | 0.050 | 0.025 | 1.0 | 32 | >150 | 2,210 |
2 | 0.050 | 0.050 | 1.0 | 33 | >150 | 2,142 |
3 | 0.050 | 0.075 | 1.0 | 34 | >150 | 2,144 |
4 | 0.050 | 0.100 | 1.0 | 37 | >150 | 2,150 |
5 | 0.075 | 0.025 | 1.0 | 35 | >150 | 2,177 |
6 | 0.075 | 0.050 | 1.0 | 37 | >150 | 2,182 |
7 | 0.075 | 0.075 | 1.0 | 39 | >150 | 2,179 |
8 | 0.075 | 0.100 | 1.0 | 41 | 132 | 2,145 |
9 | 0.100 | 0.025 | 1.0 | 43 | >150 | 2,178 |
10 | 0.100 | 0.050 | 1.0 | 42 | >150 | 2,230 |
11 | 0.100 | 0.075 | 1.0 | 44 | >150 | 2,197 |
12 | 0.100 | 0.100 | 1.0 | 46 | 120 | 2,193 |
13 | 0.125 | 0.025 | 1.0 | 53 | 134 | 2,148 |
14 | 0.125 | 0.050 | 1.0 | 54 | 128 | 2,133 |
15 | 0.125 | 0.075 | 1.0 | 49 | 112 | 2,164 |
16 | 0.125 | 0.100 | 1.0 | 52 | 94 | 2,156 |
17 | 0.100 | 0.100 | 1.5 | 38 | 107 | 2,084 |
18 | 0.100 | 0.100 | 2.0 | 37 | 83 | 2,129 |
19 | 0.100 | 0.100 | 2.5 | 37 | 57 | 2,182 |
20 | 0.100 | 0.100 | 3.0 | 36 | 32 | 2,254 |
# | NaOH:fly ash ratio | Na2SiO3:fly ash ratio | Sand:fly ash ratio | 7 day hardened density (kg/m3) | 7 day compressive strength (MPa) |
---|---|---|---|---|---|
1 | 0.050 | 0.025 | 1.0 | 2,117 | 5 |
2 | 0.050 | 0.050 | 1.0 | 2,113 | 8 |
3 | 0.050 | 0.075 | 1.0 | 2,121 | 10 |
4 | 0.050 | 0.100 | 1.0 | 2,134 | 20 |
5 | 0.075 | 0.025 | 1.0 | 2,161 | 16 |
6 | 0.075 | 0.050 | 1.0 | 2,161 | 26 |
7 | 0.075 | 0.075 | 1.0 | 2,158 | 32 |
8 | 0.075 | 0.100 | 1.0 | 2,138 | 32 |
9 | 0.100 | 0.025 | 1.0 | 2,174 | 26 |
10 | 0.100 | 0.050 | 1.0 | 2,167 | 32 |
11 | 0.100 | 0.075 | 1.0 | 2,187 | 35 |
12 | 0.100 | 0.100 | 1.0 | 2,186 | 40 |
13 | 0.125 | 0.025 | 1.0 | 2,119 | 23 |
14 | 0.125 | 0.050 | 1.0 | 2,136 | 25 |
15 | 0.125 | 0.075 | 1.0 | 2,151 | 27 |
16 | 0.125 | 0.100 | 1.0 | 2,138 | 33 |
17 | 0.100 | 0.100 | 1.5 | 2,041 | 32 |
18 | 0.100 | 0.100 | 2.0 | 2,091 | 39 |
19 | 0.100 | 0.100 | 2.5 | 2,136 | 36 |
20 | 0.100 | 0.100 | 3.0 | 2,220 | 36 |
4.1 Temperature
4.2 Flow
4.3 Density
4.4 Compressive Strength
Source | Sum of squares | Degrees of freedom | Mean squares | F ratio | p (significance) |
---|---|---|---|---|---|
NaOH:fly ash ratio | 3,271.01 | 3 | 1,090.34 | 196.48 | <0.01 |
Na2SiO3:fly ash ratio | 1,252.84 | 3 | 417.61 | 75.25 | <0.01 |
NaOH × Na2SiO3 | 182.93 | 9 | 20.33 | 3.66 | <0.01 |
Error | 177.58 | 32 | 5.55 | – | – |
Total | 4,884.36 | 47 | – | – | – |