Influence of ilmenite, garnet, and rutile on the hardened, thermal resistance, and radiation shielding properties of UHPHWC

Abstract

This study evaluates Ultra-High Performance Heavyweight Concrete (UHPHWC) incorporating fine aggregates such as garnet, rutile, and ilmenite to enhance density, mechanical properties, thermal stability, and radiation shielding efficiency. The effects of these aggregates as partial or full sand replacements were investigated under standard and elevated temperatures. Experimental tests assessed workability, Strength, and radiation shielding (RS) using gamma sources Cs-137 (662 keV) and Co-60 (average energy ≈ 1250 keV). Results showed that ilmenite-based mixtures achieved the highest density (3895 kg/m³) and optimal mechanical performance, with the 50% and–50% ilmenite mix recording the highest strength 172 MPa. Increased ilmenite content significantly improved radiation attenuation, achieving the lowest Half-Value Layer (HVL) and Tenth-Value Layer (TVL). Despite exposure to 800°C, ilmenite-based UHPHWC retained superior shielding efficiency, with a linear attenuation coefficient (LAC) reduction of only 16.9%–18% for Co-60 and 15.2%–16.7% for Cs-137, while maintaining 31.3% of its original compressive strength. The lowest permeability (1.17 × 10−11 cm/sec) was observed in ilmenite-rich mixtures, reinforcing their suitability for water-resistant applications. This study confirms that ilmenite significantly enhances UHPHWC’s durability, mechanical strength, thermal stability, and radiation shielding properties, making it an ideal material for applications requiring fire resistance and superior radiation attenuation.