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Delayed setting time for alkali-activated slag composites using activator containing SiO2 and Na2O Cover

Delayed setting time for alkali-activated slag composites using activator containing SiO2 and Na2O

Materials Science-Poland
Volume 39 (2021): Issue 4 (December 2021)
By: ,  ,   and    
Open Access
|Apr 2022
Figures & tables

Figures & Tables

Table 1

Chemical and physical properties of slag

Main chemical composition of slag (by weight %)SiO233.87
Al2O314.42
Fe2O30.69
CaO39.54
MgO5.35
SO32.47
Basicity coefficient Kb(CaO+MgO)/(SiO2+Al2O3)0.93
Physical propertiesSpecific weight2.90
Ignition loss (%)0.28

[i] Note: Results of the author's analysis using X-ray fluorescence.

Table 2

Grain size distribution of the slag

Sieve sizeNo. 50No. 100No. 200No. 325Bottom
Cumulative retained percentage (%)0.200.4032.5077.23100.00
Table 3

Chemical composition of sodium hydroxide used in experiments

Chemical compositionContent (wt. %, maximum)
Chloride (Cl)0.005
Sulfate (SO4)0.003
Silicate (SiO2)0.01
Phosphate (PO4)0.001
Heavy metal (As, Pb)0.001
Iron (Fe)0.0007
Aluminum (Al)0.003
Calcium (Ca)0.001
Magnesium (Mg)0.0005
Potassium (K)0.1
Total nitrogen (N)0.001
Arsenic (As)0.0002
Sodium carbonate (Na2CO3)2.0
Assay (NaOH)95.0

[i] Note: Results were obtained from the supplier.

Table 4

Chemical composition of sodium silicate used in the experiments

ItemsResults
Water-insolubles (%)0.01 (max)
SiO2 (%)37.0
Na2O (%)17.7
Mole ratio2.16
Fe (%)0.02 (max)

[i] Note: Results were obtained from the supplier.

Table 5

Mix designs

Activator (g/l)Weight %
SiO2Na2ONaOHNa2SiO3H2OSlag
60600.0130.0540.2660.667
60800.0220.0540.2570.667
601000.0310.0540.2490.667
601200.0390.0540.2400.667
80600.0090.0720.2520.667
80800.0180.0720.2430.667
801000.0270.0720.2350.667
801200.0350.0720.2260.667
100600.0050.0900.2380.667
100800.0140.0900.2290.667
1001000.0220.0900.2210.667
1001200.0310.0900.2120.667
120600.0010.1080.2240.667
120800.0100.1080.2160.667
1201000.0180.1080.2070.667
1201200.0270.1080.1980.667
Fig. 1

pH value of activator as a function of SiO2 concentration under various Na2O concentrations

Fig. 2

pH values of activators with fixed alkali modulus of SiO2/Na2O = 1

Fig. 3

pH values of activators with fixed total alkali content of SiO2+Na2O = 160 g/l or 200 g/l

Fig. 4

Relationship between SiO2/Na2O and pH value of activator

Fig. 5

Relationship between SiO2+Na2O and the pH value of activator

Fig. 6

Setting time (Na2O = 60–120 g/l): (A) initial time; (B) final time

Fig. 7

Setting time under SiO2/Na2O = 1: (A) initial time; (B) final time

Fig. 8

Setting times under SiO2+Na2O = 160 g/l or 200 g/l: (A) initial time; (B) final time

Fig. 9

Relationship between setting time and SiO2/Na2O: (A) initial time; (B) final time

Fig. 10

Relationship between setting time and SiO2+Na2O: (A) initial time; (B) final time

Fig. 11

SEM photos (1,000× magnification): (A) SiO2 = 120 g/l and Na2O = 120 g/l for 3 days; (B) SiO2 = 80 g/l and Na2O = 80 g/l for 3 days. SEM, scanning electron microscopy

DOI: https://doi.org/10.2478/msp-2021-0045 | Journal eISSN: 2083-134X (formerly 2083-124X) | Journal ISSN: 2083-1331
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Language: English
Page range: 570 - 579
Submitted on: Jan 7, 2022
Accepted on: Mar 6, 2022
Published on: Apr 26, 2022
Published by: Wroclaw University of Science and Technology
In partnership with: Paradigm Publishing Services
Keywords:
alkali-activated materials,
setting time,
silicate-based activator,
microstructures
Related subjects:
Materials sciences,
Materials sciences, other,
Nanomaterials,
Functional and smart materials,
Materials characterization and properties

© 2022 Chi-Che Hung, Wei-Ting Lin, Wei-Chung Yeih, Jiang-Jhy Chang, published by Wroclaw University of Science and Technology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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