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Abstract <p>The increasing use of nuclear technology in medicine, industry, and energy requires effective durable radiation shielding. This study aimed to develop and characterize nano-modified cementitious composites for enhanced gamma-ray shielding with quantitative structure-property relationships. Two-year-aged cementitious composites were prepared by partially replacing ordinary Portland cement with 5 wt% nano-silica or nano-alumina, labeled Si–C and Al–C, respectively, alongside unmodified cement (B-C) as a reference. Comprehensive multi-scale characterization included density measurement, surface area and porosity analysis (BET), particle size and colloidal stability assessment (DLS and zeta-potential), phase analysis (XRD), morphological observation (SEM-EDX), and chemical bonding analysis (FTIR). Density values were 2.78, 2.81, and 2.92 ±0.01 g·cm<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(^{-3}\)</EquationSource> </InlineEquation> for Si–C, B–C, and Al–C, respectively. BET analysis showed that Si–C and Al–C have 3.1–4.4-fold higher surface areas (290.11–416.07 m<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(^{2}\)</EquationSource> </InlineEquation>/g) and smaller pores (6–9 nm) than B–C (94.64 m<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(^{2}\)</EquationSource> </InlineEquation>/g, 28.82 nm). DLS/zeta-potential measurements showed particle sizes of 48.4 ±2.1 nm (Si–C) and 78.8 ±3.5 nm (Al–C) with –15.6 to –17.8 mV zeta-potentials versus B–C (1718 ±35.2 nm, –2.0 mV), confirming enhanced electrostatic stabilization and nano-modifiers dispersion. Quantitative XRD phase analysis revealed that Si–C exhibited significantly higher tobermorite content (53.6%) compared to B–C (37.7%) and Al–C (35.5%), indicating enhanced pozzolanic reactivity and C–S–H gel formation. Gamma-ray shielding parameters-including linear and mass attenuation coefficients (LAC, MAC), half- and tenth-value layers (HVL, TVL), effective atomic number (Z<InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(_{eff}\)</EquationSource> </InlineEquation>), and exposure and energy absorption buildup factors (EBF, EABF) were evaluated over an energy range of 1 keV to 100 GeV. Calculations were performed using the Py-MLBUF (Python Machine Learning Buildup Factor) code, and the Py-AMA.Seidy model, validated against NIST XCOM data (differences &lt;0.4%). Al-C showed the highest LAC (53.37 cm<InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(^{-1}\)</EquationSource> </InlineEquation> at 0.015 MeV) and the lowest HVL and TVL, consistent with its highest density and increased Al/Fe content. The Z<InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(_{eff}\)</EquationSource> </InlineEquation> values ranged from <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\sim\)</EquationSource> </InlineEquation> 11.8 to <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(\sim\)</EquationSource> </InlineEquation> 17.3, with Al–C exhibiting the highest values. Buildup factors (EBF/EABF) at 1 mean free path (mfp) were lowest for Al–C, indicating reduced secondary photon contribution. Double-layer shielding analysis revealed that placing B–C as the first layer, followed by Si–C or Al–C reduced double-layer buildup factors by 15–25% compared to the reverse order. Microstructural characterization confirmed that nano-silica promoted a dense, homogeneous C–S–H-rich matrix with high tobermorite content, while nano-alumina increased density and promoted C–A–S-H formation. The established structure–density–shielding relationships demonstrate that Al–C is a promising candidate for advanced radiation shielding in nuclear, medical, and industrial facilities.</p>

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Radiation shielding and microstructural characteristics of nano-silica and nano-alumina modified cement composites

  • 期刊论文

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  • 发表日期：

    2026年6月22日

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  • Arzaq Baiuomy,
  • Ahmed A. Galhoum,
  • Ahmed M. A. El-Seidy,
  • Hoda Abou-Shady,
  • Soha M. Abd El Wahab,
  • Rehab O. Abdel Rahman

摘要

Abstract

The increasing use of nuclear technology in medicine, industry, and energy requires effective durable radiation shielding. This study aimed to develop and characterize nano-modified cementitious composites for enhanced gamma-ray shielding with quantitative structure-property relationships. Two-year-aged cementitious composites were prepared by partially replacing ordinary Portland cement with 5 wt% nano-silica or nano-alumina, labeled Si–C and Al–C, respectively, alongside unmodified cement (B-C) as a reference. Comprehensive multi-scale characterization included density measurement, surface area and porosity analysis (BET), particle size and colloidal stability assessment (DLS and zeta-potential), phase analysis (XRD), morphological observation (SEM-EDX), and chemical bonding analysis (FTIR). Density values were 2.78, 2.81, and 2.92 ±0.01 g·cm \(^{-3}\) for Si–C, B–C, and Al–C, respectively. BET analysis showed that Si–C and Al–C have 3.1–4.4-fold higher surface areas (290.11–416.07 m \(^{2}\) /g) and smaller pores (6–9 nm) than B–C (94.64 m \(^{2}\) /g, 28.82 nm). DLS/zeta-potential measurements showed particle sizes of 48.4 ±2.1 nm (Si–C) and 78.8 ±3.5 nm (Al–C) with –15.6 to –17.8 mV zeta-potentials versus B–C (1718 ±35.2 nm, –2.0 mV), confirming enhanced electrostatic stabilization and nano-modifiers dispersion. Quantitative XRD phase analysis revealed that Si–C exhibited significantly higher tobermorite content (53.6%) compared to B–C (37.7%) and Al–C (35.5%), indicating enhanced pozzolanic reactivity and C–S–H gel formation. Gamma-ray shielding parameters-including linear and mass attenuation coefficients (LAC, MAC), half- and tenth-value layers (HVL, TVL), effective atomic number (Z \(_{eff}\) ), and exposure and energy absorption buildup factors (EBF, EABF) were evaluated over an energy range of 1 keV to 100 GeV. Calculations were performed using the Py-MLBUF (Python Machine Learning Buildup Factor) code, and the Py-AMA.Seidy model, validated against NIST XCOM data (differences <0.4%). Al-C showed the highest LAC (53.37 cm \(^{-1}\) at 0.015 MeV) and the lowest HVL and TVL, consistent with its highest density and increased Al/Fe content. The Z \(_{eff}\) values ranged from \(\sim\) 11.8 to \(\sim\) 17.3, with Al–C exhibiting the highest values. Buildup factors (EBF/EABF) at 1 mean free path (mfp) were lowest for Al–C, indicating reduced secondary photon contribution. Double-layer shielding analysis revealed that placing B–C as the first layer, followed by Si–C or Al–C reduced double-layer buildup factors by 15–25% compared to the reverse order. Microstructural characterization confirmed that nano-silica promoted a dense, homogeneous C–S–H-rich matrix with high tobermorite content, while nano-alumina increased density and promoted C–A–S-H formation. The established structure–density–shielding relationships demonstrate that Al–C is a promising candidate for advanced radiation shielding in nuclear, medical, and industrial facilities.