Use of Different Fine Aggregates in Ultra-High-Performance Concrete (UHPC) for Structural Radiation Shielding

¹ Dura Technology Sdn. Bhd., 31200 Chemor Perak, Malaysia
² Agensi Nuklear Malaysia, 43000 Kajang, Bangi, Malaysia
³ Public Works Department Malaysia, 50582 Kuala Lumpur, Malaysia
⁴ Swinburne University of Technology, 3122 Victoria, Australia
⁵ Monash University Malaysia, 47500 Bandar Sunway, Malaysia

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The potential of bauxite (Bx) as a radiation-shielding material remains largely underexplored, despite its availability in Malaysia and its established use in conventional concrete. Moreover, its performance within ultra-high-performance concrete (UHPC) has not been systematically evaluated. In this study, bauxite is employed as a full replacement for fine aggregates in UHPC, and its performance is compared against UHPC mixtures incorporating five other fine aggregates: silica sand (Ss), hematite (Hm), barite (Br), Amang (Am), and lead glass (Lg). The investigation focuses on density, workability, compressive strength, modulus of elasticity (MOE), and attenuation characteristics using ⁶⁰Co and ¹³⁷Cs gamma (γ)-ray sources. The results show that fine aggregate density strongly governs shielding efficiency, with UHPC-Br achieving the highest linear attenuation coefficient (µ) and the lowest half-value layer (HVL) and tenth-value layer (TVL), followed closely by UHPC-Am and UHPC-Bx, confirming their suitability for high-performance radiation shielding. UHPC-Br is preferred when shielding efficiency is the primary requirement, and lower mechanical strength is acceptable. UHPC-Am and UHPC-Bx provide a balanced combination of radiation shielding and mechanical strength, especially UHPC-Bx, which, due to its superior 250 MPa compressive strength and 63.9MPa MOE, is particularly suitable for military-grade or high-load-bearing radiation-shielding structures. In contrast, UHPC-Ss, UHPC-Hm, and UHPC-Lg exhibited weaker attenuation despite acceptable mechanical performance. In comparison, from an economic and resource-availability standpoint, silica sand remains the most practical fine aggregate for cost-sensitive UHPC radiation-shielding applications.