Performance evaluation of ultra-high-performance fiber-reinforced concrete incorporating waste OLED glass powder as a cement replacement

In this study, the potential of waste organic light-emitting diode (OLED) display glass powder as a sustainable pozzolanic material for partial cement replacement in ultra-high-performance fiber-reinforced concrete (UHPFRC) was investigated. While conventional UHPFRC has excellent strength and durability, its high cement content raises environmental concerns. OLED glass, which is rich in amorphous silica and free from backlight or plastic layers, offers a recyclable alternative to conventional binders. By replacing ordinary Portland cement with OLED powder at varying dosages (0–75 %), the effects on hydration behavior, microstructure, and mechanical performance were investigated. At a 25 % replacement level, the formation of additional C-(A-)S-H gels and lower porosity enhanced both compressive strength and fiber–matrix interfacial bonding. Single-fiber pull-out tests and microstructural imaging (atomic force microscopy, scanning electron microscopy, and energy dispersive X-ray) confirmed stronger bond strength and denser matrix morphology. Under tensile loading, digital image correlation showed effective crack dispersion and finer crack widths, indicating improved ductility and crack control. Life-cycle analysis showed that the 25 % OLED mix reduced CO₂ emissions and embodied energy by 15.7 % and 11.3 %, respectively, with minimal cost increase. These results highlight the suitability of OLED waste as a high-performance, eco-efficient binder that promotes both mechanical improvement and environmental sustainability of the next generation of UHPFRC.