Assessment of UHPC with Various Particle Distributions (q) and Low Cement Consumption

Ultra-high-performance concrete (UHPC) has been increasingly adopted in applications requiring superior mechanical performance and high durability under aggressive environments. However, its large-scale use is still limited by the high binder content and the lack of a standardized mix design methodology. Among the existing approaches, particle packing-based mix design methods have shown the most promising results, optimizing the composite structure and enabling efficient material proportioning. This study aimed to evaluate the influence of the particle distribution coefficient (q = 0.20 and 0.25) and the cement consumption ratio (15%, 20%, and 25%) on achieving the lowest packing deviation index (PDI) values using a rational UHPC mix design method. The results indicated that increasing q allowed a reduction of up to 15% in cement content, corresponding to 106 kg/m3 less binder. In contrast, changes in cement consumption, which led to different PDI values for the same q, had a significant effect on compressive strength. Mixtures with 20% cement and consumption of 598 kg/m3 exhibited the lowest PDI values (180 and 190) and the highest 91-day compressive strengths (147.0 and 151.1 MPa). Fiber reinforcement improved toughness and post-elastic energy absorption capacity. Overall, UHPC with reduced cement content and high mechanical performance can be achieved using a rational mix design method when an appropriate q value is selected.