Research on the design and multi-dimensional performance enhancement of ultra-high-performance concrete based on electric arc furnace slag

Ultra-high-performance concrete (UHPC) highly relies on polycarboxylate superplasticizer (PCE) during preparation, but PCE's side effects, such as expanding fine pores and delaying hydration, severely restrict UHPC's comprehensive performance. This study investigates the synergistic optimization of UHPC properties using spherical electric arc furnace slag (EAFS) and PCE. Seven UHPC mixtures with varying EAFS replacement ratios (0 %, 30 %, 70 %, 100 % by volume) and PCE contents (9 %-15 %) were designed to systematically evaluate their fresh properties, durability, and impact resistance. Results show that the EAFS-PCE synergism alleviates hydration delay, improves flowability by 6.16 %, and enhances mechanical properties, while reducing PCE dosage by 40 %. Compared to the control group, porosity decreases by 48.98 %. In durability tests, matrix densification and EAFS inclusion significantly enhance shrinkage resistance (microstrain reduced by 312.89 με). Freeze-thaw experiments indicate porosity is the primary factor affecting frost resistance, followed by strength. Impact tests reveal that concrete composition, particularly EAFS, significantly reduces penetration depth, highlighting that compressive strength alone cannot fully characterize UHPC's impact resistance. This study provides new insights for optimizing UHPC performance and promoting high-value utilization of industrial waste.