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Alkali-Activated Materials from Diverse Solid Precursors: Structural, Mechanical and Radiological Properties.
Nataša Mladenović Nikolić1, Marija Ivanović1, Snežana Nenadović1
1Department of Materials, "Vinča" Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, 11000 Belgrade, Serbia.
Gels (Basel, Switzerland)
|March 27, 2026
Summary
Alkali-activated materials using wood ash and metakaolin show promising results. These materials effectively immobilize radionuclides, making them safe for construction applications.
Area of Science:
- Materials Science
- Geochemistry
- Environmental Science
Background:
- Alkali-activated materials (AAMs) offer sustainable alternatives to traditional cement.
- Wood ash (WA) and metakaolin (MK) are potential precursors for AAMs.
- Understanding the influence of alkali activators on AAM properties is crucial.
Purpose of the Study:
- To investigate the gel characteristics of AAMs synthesized from WA and MK.
- To explore the impact of precursor type and NaOH concentration on AAM properties.
- To assess the radiological safety of these AAMs for construction.
Main Methods:
- Synthesis of AAMs using WA and MK with varying NaOH concentrations (6 M, 12 M).
- Characterization using X-ray fluorescence (XRF), DRIFT, XRD, and SEM-EDS.
- Evaluation of mechanical properties (compressive strength).
- Quantification of radionuclides via gamma-spectrometry.
Main Results:
- FTIR confirmed geopolymer network formation; XRD showed crystalline phases in an amorphous matrix.
- Metakaolin-based AAMs (12 M) achieved ~14 MPa compressive strength.
- Wood ash-based AAMs exhibited lower strength (~4 MPa at 6 M, ~0.5 MPa at 12 M) due to precursor composition.
- Alkali activation significantly reduced radiological hazard parameters (Raeq, Hex, Iγ), with values below safety limits.
Conclusions:
- AAMs synthesized from WA and MK demonstrate tunable physicochemical and mechanical properties.
- Increasing NaOH concentration enhances radionuclide immobilization within the geopolymer matrix.
- These AAMs are suitable for safe construction applications from a radiation protection standpoint.
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