Microstructural Analysis and Radiological Characterization of Alkali-Activated Materials Based on Aluminosilicate...

Area of Science:

• Materials Science
• Environmental Science
• Geochemistry

Background:

• Alkali-activated materials (AAMs) are synthesized from aluminosilicate precursors like fly ash and metakaolin.
• Fly ash and wood ash, by-products of combustion, are sustainable sources for AAMs.
• AAMs exhibit attractive properties such as thermal stability, high porosity, and low production energy.

Purpose of the Study:

• To evaluate the physico-chemical properties, microstructure, and radiological impacts of AAMs derived from fly and wood ash.
• To assess the safety of using these AAMs, termed "green cements," in construction, especially concerning naturally occurring radionuclides (NORs).

Main Methods:

• Synthesis of AAMs using alkali-activation of fly ash, metakaolin, and wood ash.
• Determination of radionuclide content via gamma-ray spectrometry.
• Characterization of AAMs using X-ray Diffraction (XRD), DRIFT, Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM).

Main Results:

• AAMs demonstrated a lower activity concentration of radionuclides compared to their raw precursor materials.
• The external absorbed gamma dose rate ranged from 74.7 to 107.3 nGy/h.
• External radiation hazard index values were between 0.445 and 0.628 Bq/kg, indicating safety.

Conclusions:

• The activity concentration measurements confirm the potential for safe application of these AAMs in building construction.
• The study validates the use of waste materials like fly ash and wood ash in creating sustainable and safe "green cements".