1 Introduction
2 Experimental Program
2.1 Materials
Chemical composition (%) | Portland cement Type I | Fly ash |
---|---|---|
Silicon dioxide, SiO2 | 20.10 | 35.20 |
Aluminum oxide, Al2O3 | 5.20 | 19.20 |
Iron oxide, Fe2O3 | 3.15 | 17.81 |
Calcium oxide, CaO | 60.24 | 16.65 |
Magnesium oxide, MgO | 1.13 | – |
Sodium oxide, Na2O | 0.11 | 0.63 |
Potassium oxide, K2O | 0.43 | 2.44 |
Sulfur trioxide, SO3 | 2.42 | 1.50 |
LOI | 2.03 | 0.15 |
2.2 Specimens and Test Program
Mix | Mixture proportion (by weight) | ||||||||
---|---|---|---|---|---|---|---|---|---|
Cement Type I | Fly ash | Fine aggregate | Water | NaOH solution | |||||
0.25 molar | 0.50 molar | 0.75 molar | 1.00 molar | 1.25 molar | |||||
IF 30 | 0.70 | 0.30 | 2.75 | 0.63 | |||||
IF30–0.25 M | 0.70 | 0.30 | 2.75 | 0.59 | |||||
IF30–0.50 M | 0.70 | 0.30 | 2.75 | 0.58 | |||||
IF30–0.75 M | 0.70 | 0.30 | 2.75 | 0.59 | |||||
IF30–1.00 M | 0.70 | 0.30 | 2.75 | 0.60 | |||||
IF30–1.25 M | 0.70 | 0.30 | 2.75 | 0.61 | |||||
IF 40 | 0.60 | 0.40 | 2.75 | 0.62 | |||||
IF40–0.25 M | 0.60 | 0.40 | 2.75 | 0.58 | |||||
IF40–0.50 M | 0.60 | 0.40 | 2.75 | 0.58 | |||||
IF40–0.75 M | 0.60 | 0.40 | 2.75 | 0.58 | |||||
IF40–1.00 M | 0.60 | 0.40 | 2.75 | 0.59 | |||||
IF40–1.25 M | 0.60 | 0.40 | 2.75 | 0.60 | |||||
IF 50 | 0.50 | 0.50 | 2.75 | 0.61 | |||||
IF50–0.25 M | 0.50 | 0.50 | 2.75 | 0.58 | |||||
IF50–0.50 M | 0.50 | 0.50 | 2.75 | 0.57 | |||||
IF50–0.75 M | 0.50 | 0.50 | 2.75 | 0.57 | |||||
IF50–1.00 M | 0.50 | 0.50 | 2.75 | 0.58 | |||||
IF50–1.25 M | 0.50 | 0.50 | 2.75 | 0.60 | |||||
IF 60 | 0.40 | 0.60 | 2.75 | 0.61 | |||||
IF60–0.25 M | 0.40 | 0.60 | 2.75 | 0.57 | |||||
IF60–0.50 M | 0.40 | 0.60 | 2.75 | 0.56 | |||||
IF60–0.75 M | 0.40 | 0.60 | 2.75 | 0.56 | |||||
IF60–1.00 M | 0.40 | 0.60 | 2.75 | 0.58 | |||||
IF60–1.25 M | 0.40 | 0.60 | 2.75 | 0.59 |
3 Results and Discussion
3.1 Properties of Pastes
3.2 Effect of NaOH Concentration on Compressive Strength of Mortar
Mix | Compressive strength (MPa) | Normalized compressive strength (%) | ||||||
---|---|---|---|---|---|---|---|---|
3 days | 7 days | 14 days | 28 days | 60 days | 90 days | 28 days | 90 days | |
IF 30 | 12.9 | 14.6 | 18.1 | 21.9 | 26.8 | 30.2 | 100.0 | 100.0 |
IF30–0.25 M | 12.5 | 13.6 | 17.4 | 23.2 | 27.4 | 30.7 | 106.0 | 101.9 |
IF30–0.50 M | 16.7 | 18.2 | 21.6 | 27.1 | 30.6 | 33.9 | 123.7 | 112.2 |
IF30–0.75 M | 12.9 | 15.1 | 18.6 | 22.5 | 25.9 | 28.4 | 102.7 | 94.0 |
IF30–1.00 M | 11.0 | 12.1 | 14.3 | 19.3 | 22.4 | 24.7 | 88.3 | 81.8 |
IF30–1.25 M | 8.1 | 8.3 | 11.7 | 16.0 | 18.0 | 19.3 | 72.9 | 63.9 |
IF 40 | 10.8 | 10.9 | 14.7 | 18.7 | 22.7 | 25.2 | 100.0 | 100.0 |
IF40–0.25 M | 10.7 | 12.3 | 14.1 | 19.1 | 22.2 | 24.5 | 102.4 | 97.1 |
IF40–0.50 M | 12.5 | 15.2 | 18.3 | 22.9 | 25.0 | 27.5 | 122.4 | 109.0 |
IF40–0.75 M | 10.7 | 12.8 | 15.5 | 19.5 | 21.2 | 22.9 | 104.4 | 90.9 |
IF40–1.00 M | 10.4 | 12.6 | 15.5 | 18.3 | 20.1 | 20.9 | 98.2 | 83.0 |
IF40–1.25 M | 6.7 | 9.4 | 11.9 | 14.7 | 18.7 | 19.5 | 78.9 | 77.5 |
IF 50 | 8.4 | 10.2 | 13.0 | 16.6 | 19.3 | 21.3 | 100.0 | 100.0 |
IF50–0.25 M | 8.6 | 10.8 | 15.9 | 19.0 | 22.4 | 25.1 | 114.3 | 117.8 |
IF50–0.50 M | 13.8 | 15.8 | 20.2 | 24.2 | 26.8 | 28.2 | 145.8 | 132.2 |
IF50–0.75 M | 9.2 | 11.9 | 15.4 | 19.0 | 23.4 | 27.8 | 114.3 | 130.5 |
IF50–1.00 M | 9.4 | 11.9 | 15.9 | 19.7 | 21.7 | 22.8 | 118.8 | 106.9 |
IF50–1.25 M | 7.4 | 9.1 | 12.6 | 15.0 | 18.0 | 20.5 | 90.7 | 95.9 |
IF 60 | 7.4 | 8.3 | 10.4 | 14.9 | 16.2 | 16.8 | 100.0 | 100.0 |
IF60–0.25 M | 7.8 | 10.4 | 13.1 | 15.9 | 17.9 | 20.2 | 106.7 | 120.4 |
IF60–0.50 M | 9.4 | 13.5 | 15.9 | 18.0 | 19.6 | 22.2 | 121.1 | 132.8 |
IF60–0.75 M | 8.1 | 12.6 | 13.6 | 18.5 | 21.9 | 23.6 | 124.6 | 140.7 |
IF60–1.00 M | 6.4 | 10.0 | 12.4 | 15.3 | 20.0 | 22.9 | 102.7 | 136.4 |
IF60–1.25 M | 5.7 | 8.4 | 11.0 | 13.0 | 15.2 | 16.9 | 87.3 | 100.8 |