Effects of alumina, bauxite, silicon carbide or quartz reinforcement particles on the performance of engineered UHPC with compressive strength exceeding 200   MPa

The effects of different reinforcement particles – alumina powder (AP), bauxite powder (BP), quartz powder (QP) and silicon carbide (SCP) – on the fresh-state behaviour, mechanical performance, reliability and dynamic mechanical properties of engineered ultra-high-performance concrete (UHPC) formulations were investigated. White Portland cement (PC-W) and oil well cement (PC-G) were combined with silica fume at a low water-to-binder ratio of 0.23. The UHPCs were subjected to thermal curing at 90°C for 72 h. Fresh-state properties were assessed through mini-slump and oscillatory rheometry, while hardened-state performance was evaluated by compressive, tensile, flexural, shear and dynamic mechanical analyses. Weibull statistics were applied to assess mechanical reliability. The PC-G-based formulations consistently outperformed the PC-W systems, achieving compressive strengths exceeding 200 MPa and exhibiting lower variability and higher reliability. QP maximised compressive and shear strength, AP enhanced tensile strength and stiffness, BP provided superior flexural strength and toughness, and SCP improved ductility despite lower peak strengths. Dynamic mechanical analysis confirmed excellent viscoelastic stability under cyclic loading, particularly for the PC-G systems. Overall, the PC-G-BP formulation demonstrated the best combination of mechanical properties – it was the only system to simultaneously achieve high compressive strength (>200 MPa), superior flexural toughness and stable viscoelastic response under cyclic loading without trade-offs among these key performance parameters.