الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The revolution in construction field and new challenges to produce concrete with superior characteristics of strength has paid our attention to create new types of concrete such high performance concrete (HPC). The present study aims to develop a new heavy weight concrete type called high-performance heavyweight concrete (HPHWC). It’s characterized by resisting various nuclear radiation and an elevated temperature. Sustainable construction has attempted to alleviate the negative environmental consequences of the construction industry (the largest user of natural resources). Consequently, it is essential to continually seek alternatives in the concrete industry.
This study introduces new materials that can be utilized as partial replacement for fine aggregate to manufacture HPHWC. These materials include hematite, black sand (BS), ilmenite (I), and magnetite (M) with substitution ratios of 50% and 100% of fine aggregates. Using various minerals aimed to balance between all HWHPC properties, not only the shielding properties. The BS is a promising concrete shielding material rich in specific minerals, and these minerals get sand with very special merit. It improves concrete properties, particularly at high temperatures, if used carefully. Black sand is a natural mineral found on the shore and along riverbeds composed of iron titanates (ilmenite) and minor oxides like silicon, magnesium, and magnetite. The deposits of Egyptian black sand are the erosional byproducts of the metamorphic rocks and crystalline igneous brought by the Nile River from the Ethiopian Plateau and South Sudan.
The properties of fresh concrete were obtained using a slump flow test and slump test. The density and hardened properties of compressive, splitting tensile, flexural strength, modulus of elasticity, abrasion resistance, and sulfate attack were studied. The tenth-value layer (TVL), linear attenuation coefficient (μ), and half-value layer (HVL) for concrete samples were determined using a gamma source of Co-60 through the thicknesses of 2.5, 5, 7.5, 10, 12.5, and 15 cm. Test specimens were subjected to elevated temperatures at 300 oC, 500 oC and 700 oC for 2hours. Specimens were exposed to sever sulfate attack through drying-wetting cycles in sodium sulfate solution with concentrations of 5%, 10% and 20% for 180 days. Microstructure
analyses were conducted by scanning electron microscope and energy dispersive x-ray.
Finally, the results indicated the possibility of using hematite, black sand, ilmenite, and magnetite as a construction material in structures exposed to high temperatures and radiation shielding, especially gamma radiation. The use of nano ferrosilicon (NFS) as an addition for cement led to good results for the mechanical and Radiation shielding properties of ultra-high performance heavyweight concrete (UHPHWC).