New insights into the impact of iron-rich phases inside thermally treated glauconite on the gamma radiation shielding capability of serpentine/glauconite-based geopolymer

Abstract This study investigates the gamma-ray shielding performance of alkali-activated materials derived from thermally treated glauconite (TTG) and thermally treated serpentine (TTS), activated by a sodium silicate solution. Three TTS/TTG binders were prepared by substituting TTS with TTG at 0%, 20%, and 40% by weight. The phase composition and microstructure of the synthesized binders (TTS/TTG-0%, TTS/TTG-20%, and TTS/TTG-40%) were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The gamma-ray shielding parameters mass attenuation coefficient (µ m ), effective atomic number (Z eff ), half value layer (HVL), and exposure build-up factor (EBF) were determined both theoretically and experimentally across a photon energy range of 0.015–15 MeV. Characterization results indicated that adding TTG led to the formation of high-density, iron-rich magnetic phases such as magnesioferrite, and magnetite, alongside hydration products. Both experimental and theoretical evaluations revealed that increasing TTG content significantly enhanced gamma-ray shielding capabilities, attributed to the presence of high atomic number elements within TTG. The measured values aligned closely with theoretical predictions. The study concludes that the incorporation of TTG improves the shielding efficiency of alkali-activated materials due to the formation of dense, magnetic phases. TTS/TTG-20% and TTS/TTG-40% binders demonstrate potential as low-cost, effective geopolymers for radiation shielding applications in nuclear, medical, and industrial fields.