TY - JOUR A1 - Yahya, Ahmed A1 - Mounir, Ahmed A1 - Al-Motori, Shirin A1 - Moustafa, Ahmed A1 - Kohail, Mohamed A1 - Raab, Bastian A1 - Soltan, AbdelMonem A1 - Mohsen, Alaa T1 - Investigation of the mechanical, microstructure, thermal and gamma-ray attenuation characteristics of serpentinite and ilmenite-based concrete as bio-shielding materials JF - Materials Today Communications N2 - Owing to nuclear technology’s significance in medical, industrial and military applications, this study assessed the effectiveness of some Egyptian raw materials in the production of heavy-weight concrete to shield hazards emitted radiations. Three mix-designs containing different coarser aggregates (dolomite (D), serpentinite (S) and ilmenite (Il)) were prepared. Their workability and physico-mechanical characteristics were examined. The hydrated concretes’ phase composition and microstructure were analyzed using XRD, TGA/DTG and SEM/optical-microscopy. The impact of elevated temperatures (300, 600 and 900◦C for 2 hrs) on the mechanical properties was studied. The volume stability of concrete specimens was investigated using a hot-stage microscope and thermodynamics calculations. Finally, the gamma-ray attenuation was evaluated against the 137Cs radioactive isotope with 0.662 MeV energy. The results revealed that Il-concrete has the highest slump value, highest bulk density and lowest water absorption. Also, it has the most outstanding efficiency in gamma-ray shielding; its attenuation is higher than D-concrete and S-concrete by 271.2 and 168.1 %, respectively. Replacing dolomite with serpentinite and ilmenite harms mechanical performance. However, the compressive-strength of the prepared concretes is in the range of 24.10–41.06 MPa at 28-days, achieving the building code’s requirements for structural concrete. At elevated temperature, S-concrete showed the highest compressive-strength retention and highest volume stability. Y1 - 2025 U6 - https://doi.org/10.1016/j.mtcomm.2025.113107 SN - 2352-4928 VL - 47 PB - Elsevier BV ER - TY - JOUR A1 - Abdel-Kader, Noha A1 - EL-Raoof, Fawzia Abd A1 - Sharaf-Eldin, Ahmed A1 - Elmasry, Ayat A1 - Yahya, Ahmed A1 - Zacher, Gerhard A1 - Raab, Bastian A1 - Soltan, AbdelMonem T1 - Clays to lightweight aggregates: Thermochemical modeling and industrial validation JF - Construction and Building Materials N2 - The creation of thermochemical models to forecast the dependent variables governing the bloatability of lightweight aggregates (LWAs) is the goal of this work. Laser particle size analysis, XRD, XRF, IR, TGA-DTA, SEM-EDX, Laser imaging system, µ-CT, hot-stage microscope and Factsage (8.3) thermodynamic software were used for clays and LWAs characterization in the temperature range 900–1250°C. It was found that the LWAs bloating zone occurs at 1050–1250°C with a minimum bulk density (BD) of (0.74 g/cm3) at 1250°C. During the LWAs pyroplastic state, the crystallization of anorthite from the silicate melt lowers its viscosity due mainly to the alkalis’ uptake into the anorthite lattice. However, the silicate melt is still viscous enough to trigger the reduction of hematite and consequently guarantees the evolution of bloating gases. The simultaneous association of higher evolved gas with less melt content of higher viscosity would promote the LWAs bloatability. The higher the gas that accompanied with low melt of lower viscosity would loosen the LWAs their consistency and sphericity upon their sudden cooling. Based on the LWAs bulk density and lab experimental observations, the production window limits of successful LWAs are ≥40 wt% silicate melt of 103-107 Pa.s viscosity that accompanied with (0.50–4.00 wt%) gas content. This production window has been verified by Liapor industrial kiln feed. The LWAs pyroplastic and post-quenching characteristics are all statistically significant variables (<0.05) for prediction modeling. The forecasting models are statistically verified by the multi-collinearity testing that shows VIF values <10 indicating the absence of any multi-collinearity among the models’ explanatory variables. Y1 - 2024 U6 - https://doi.org/10.1016/j.conbuildmat.2024.136580 SN - 0950-0618 VL - 432 PB - Elsevier BV ER - TY - JOUR A1 - Yahya, Ahmed A1 - Allam, Sherif A1 - Almasarawi, Ola N. A1 - Abdel-Hameed, Salwa A.M. A1 - Raab, Bastian A1 - Soltan, AbdelMonem A1 - Hamzawy, Esmat M.A. T1 - Microstructural, physico-mechanical, optical and photocatalytic characteristics of kaolin-based eucryptite glass ceramics JF - Applied Clay Science N2 - Lithium aluminosilicates glass ceramics were prepared from quarried kaolin and artificial lithium carbonate. Different techniques were used to characterize the starting batches, glasses and glass ceramics, these are: laser PSDs, XRD, XRF, DSC, SEM-EDAX, bulk density, CTE, microhardness, FTIR, UV-Vis spectrophotometer in addition to Factsage (8.3) thermodynamic modeling software. Results show that the Al/Si ratio and total impurities of kaolin-based batches influence the crystallization of non-cracked and directly bounded coated eucryptite with shielding rims of lithium metasilicates, nepheline, leucite and silicate glassy phase. Notably, the low-grade kaolin-based batch motivates the crystallization of mature lithium aluminosilicate glass ceramics microstructure which enhances the bulk density (2.41 g/cm3), apparent porosity (0.7%), water absorption (0.29%), microhardness (394 kg/mm2), thermal expansion coefficient (₋0.76×10-7°C-1) at (25-500°C) and UV-V reflectance up to 86%. The mature microstructure with shielded rimmed eucryptite exhibits outstanding photocatalytic performance, achieving up to 92% removal of MB dye. Such lithium aluminosilicate glass ceramics could be promising in microelectronics and photocatalysis applications. KW - Kaolin impuritiesLASMicrostructurePhotocatalysisThermal expansion Y1 - 2025 U6 - https://doi.org/10.1016/j.clay.2025.108024 SN - 0169-1317 VL - 279 PB - Elsevier BV ER -