This study explores the influence of sodium gluconate (SG), an organic electrolyte, on the rheology and mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC). SGwas incorporated at varying dosages (0.03%-0.15%) to assess its effects on workability, hydra- tion, porosity, and fracture…
This study explores the influence of sodium gluconate (SG), an organic electrolyte, on the rheology and mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC). SGwas incorporated at varying dosages (0.03%-0.15%) to assess its effects on workability, hydra- tion, porosity, and fracture behavior. Key findings demonstrate that SG effectively retards hydra- tion by inhibiting gypsum dissolution and AFt formation, resulting in significant delays in setting time—up to 295% with higher SG content. Furthermore, increased SG dosages improved workabil- ity, with a slump diameter increase of up to 56%, facilitating better fiber distribution and bonding. No major chemical changes were observed in the concrete matrix; however, SG decreased macro- pores (> 10µm) and increased micropores (< 0.1µm), which contributed to enhanced mechanical performance. Compressive strength rose by 9.5%, and flexural cracking initiation improved by 38% for Mix-0.15. Residual flexural strengths also showed substantial increases (up to 38%), attributed to improved fiber-matrix adhesion. These findings highlight SG’s potential to improve UHPFRC’s mechanical properties and durability, making it a promising additive for high-strength construction applications.